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Psychedelics are a subclass of hallucinogenic drugs whose primary effect is to trigger non-ordinary mental states (known as
psychedelic experience A psychedelic experience (known colloquially as a trip) is a temporary altered state of consciousness induced by the consumption of a psychedelic substance (most commonly Lysergic acid diethylamide, LSD, mescaline, psilocybin mushrooms, or N,N- ...
s or "trips") and a perceived "expansion of consciousness". Also referred to as classic hallucinogens or serotonergic hallucinogens, the term ''psychedelic'' is sometimes used more broadly to include various other types of hallucinogens as well, such as those which are atypical or adjacent to
psychedelia Psychedelia usually refers to a Aesthetics, style or aesthetic that is resembled in the psychedelic subculture of the 1960s and the psychedelic experience produced by certain psychoactive substances. This includes psychedelic art, psychedelic ...
like
salvia ''Salvia'' () is the largest genus of plants in the sage family Lamiaceae, with just under 1,000 species of shrubs, Herbaceous plant, herbaceous Perennial plant, perennials, and Annual plant, annuals. Within the Lamiaceae, ''Salvia'' is part o ...
and
MDMA 3,4-Methylenedioxymethamphetamine (MDMA), commonly known as ecstasy (tablet form), and molly (crystal form), is an empathogen–entactogenic drug with stimulant and minor Psychedelic drug, psychedelic properties. In studies, it has been used ...
, respectively. Classic psychedelics generally cause specific psychological,
visual The visual system is the physiological basis of visual perception (the ability to detect and process light). The system detects, transduces and interprets information concerning light within the visible range to construct an image and buil ...
, and auditory changes, and oftentimes a substantially
altered state of consciousness An altered state of consciousness (ASC), also called an altered state of mind, altered mental status (AMS) or mind alteration, is any condition which is significantly different from a normal waking state. It describes induced changes in one's me ...
. They have had the largest influence on science and culture, and include
mescaline Mescaline, also known as mescalin or mezcalin, and in chemical terms 3,4,5-trimethoxyphenethylamine, is a natural product, naturally occurring psychedelic drug, psychedelic alkaloid, protoalkaloid of the substituted phenethylamine class, found ...
,
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
,
psilocybin Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
, and DMT. There are a large number of both
naturally occurring A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical ...
and
synthetic Synthetic may refer to: Science * Synthetic biology * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic elements, chemical elements that are not naturally found on Earth and therefore have to be created in ...
serotonergic psychedelics. Most psychedelic drugs fall into one of the three families of chemical compounds:
tryptamines Substituted tryptamines, or simply tryptamines, also known as serotonin analogues (i.e., 5-hydroxytryptamine analogues), are organic compounds which may be thought of as being derived from tryptamine itself. The molecular structures of all trypt ...
, phenethylamines, or
lysergamides Lysergamides, also known as ergoamides or as lysergic acid amides, are amides of lysergic acid (LA). They are ergolines, with some lysergamides being found natural product, naturally in ergot as well as other fungi. Lysergamides are notable in c ...
. They produce their psychedelic effects by binding to and activating a
receptor Receptor may refer to: * Sensory receptor, in physiology, any neurite structure that, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and respond ...
in the
brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...
called the
serotonin Serotonin (), also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter with a wide range of functions in both the central nervous system (CNS) and also peripheral tissues. It is involved in mood, cognition, reward, learning, ...
5-HT2A receptor. By activating serotonin 5-HT2A receptors, they modulate the activity of key circuits in the brain involved with sensory perception and cognition. However, the exact nature of how psychedelics induce changes in perception and cognition via the serotonin 5-HT2A receptor is still unknown. The psychedelic experience is often compared to non-ordinary forms of consciousness such as those experienced in
meditation Meditation is a practice in which an individual uses a technique to train attention and awareness and detach from reflexive, "discursive thinking", achieving a mentally clear and emotionally calm and stable state, while not judging the meditat ...
,
mystical experience A religious experience (sometimes known as a spiritual experience, sacred experience, mystical experience) is a subjective experience which is interpreted within a religious framework. The concept originated in the 19th century, as a defense ag ...
s, and
near-death experience A near-death experience (NDE) is a profound personal experience associated with death or impending death, which researchers describe as having similar characteristics. When positive, which the great majority are, such experiences may encompa ...
s, which also appear to be partially underpinned by altered
default mode network In neuroscience, the default mode network (DMN), also known as the default network, default state network, or anatomically the medial frontoparietal network (M-FPN), is a large-scale brain network primarily composed of the dorsal medial prefro ...
activity. The phenomenon of
ego death Ego death is a "complete loss of subjective self-identity". The term is used in various intertwined contexts, with related meanings. The 19th-century philosopher and psychologist William James uses the synonymous term "self-surrender", and Jung ...
is often described as a key feature of the psychedelic experience. Many psychedelic drugs are illegal to possess without lawful authorisation, exemption or license worldwide under the UN conventions, with occasional exceptions for religious use or research contexts. Despite these controls, recreational use of psychedelics is common. There is also a long history of use of naturally occurring psychedelics as
entheogen Entheogens are psychoactive substances used in spiritual and religious contexts to induce altered states of consciousness. Hallucinogens such as the psilocybin found in so-called "magic" mushrooms have been used in sacred contexts since ancie ...
s dating back thousands of years. Legal barriers have made the scientific study of psychedelics more difficult. Research has been conducted, however, and studies show that psychedelics are physiologically
safe A safe (also called a strongbox or coffer) is a secure lockable enclosure used for securing valuable objects against theft or fire. A safe is usually a hollow cuboid or cylinder, with one face being removable or hinged to form a door. The body ...
and rarely lead to
addiction Addiction is a neuropsychological disorder characterized by a persistent and intense urge to use a drug or engage in a behavior that produces natural reward, despite substantial harm and other negative consequences. Repetitive drug use can ...
. Studies conducted using psilocybin in a psychotherapeutic setting reveal that psychedelic drugs may assist with treating depression,
anxiety Anxiety is an emotion characterised by an unpleasant state of inner wikt:turmoil, turmoil and includes feelings of dread over Anticipation, anticipated events. Anxiety is different from fear in that fear is defined as the emotional response ...
, alcohol addiction, and nicotine addiction. Although further research is needed, existing results suggest that psychedelics could be effective treatments for certain mental health conditions. A 2022 survey by
YouGov YouGov plc is a international Internet-based market research and data analytics firm headquartered in the UK with operations in Europe, North America, the Middle East, and Asia-Pacific. History 2000–2010 Stephan Shakespeare and Nadhim ...
found that 28% of Americans had used a psychedelic at some point in their life.


Examples

*
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
(lysergic acid diethylamide) is a derivative of lysergic acid, which is obtained from the
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
of
ergotamine Ergotamine, sold under the brand name Ergomar among others, is an ergopeptine and part of the ergot family of alkaloids; it is structurally and biochemically closely related to ergoline. It is structurally similar to several neurotransmitter ...
. Ergotamine is an
alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...
found in the fungus ''
Claviceps purpurea ''Claviceps purpurea'' is an ergot fungus that grows on the ear (botany), ears of rye and related cereal and forage plants. Consumption of Cereal, grains or seeds contaminated with the survival structure of this fungus, the ergot sclerotium, can ...
'' (ergot), which primarily infects rye. LSD is both the prototypical psychedelic and the prototypical lysergamide. As a lysergamide, LSD contains both a
tryptamine Tryptamine is an indolamine metabolite of the essential amino acid tryptophan. The chemical structure is defined by an indole—a fused benzene and pyrrole ring, and a 2-aminoethyl group at the second carbon (third aromatic atom, with the firs ...
and
phenethylamine Phenethylamine (PEA) is an organic compound, natural monoamine alkaloid, and trace amine, which acts as a central nervous system stimulant in humans. In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace ami ...
group within its structure. Uniquely among psychedelics, LSD agonises dopamine receptors as well as serotonin receptors. *
Psilocin Psilocin, also known as 4-hydroxy-''N'',''N''-dimethyltryptamine (4-HO-DMT), is a substituted tryptamine alkaloid and a serotonergic psychedelic. It is present in most psychedelic mushrooms together with its phosphorylated counterpart psilocy ...
(4-HO-DMT) is the dephosphorylated active metabolite of the
indole alkaloid Indole alkaloids are a class of alkaloids containing a structural moiety of indole; many indole alkaloids also include isoprene groups and are thus called terpene indole or secologanin tryptamine alkaloids. Containing more than 4100 known differ ...
psilocybin Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
and a
substituted tryptamine Substituted tryptamines, or simply tryptamines, also known as serotonin analogues (i.e., 5-hydroxytryptamine analogues), are organic compounds which may be thought of as being derived from tryptamine itself. The molecular structures of all trypt ...
, which is produced by hundreds of species of psilocybin-containing mushrooms. Of the classical psychedelics, psilocybin has attracted the greatest academic interest regarding its ability to manifest mystical experiences, although all psychedelics are capable of doing so to variable degrees.
4-AcO-DMT 4-Acetoxy-''N'',''N''-dimethyltryptamine (4-AcO-DMT or 4-acetoxy-DMT), also known as ''O''-acetylpsilocin or psilacetin, is a psychedelic drug of the tryptamine family related to psilocybin and psilocin. It is a synthetic derivative of psiloc ...
(''O''-acetylpsilocin or psilacetin) is a
synthetic Synthetic may refer to: Science * Synthetic biology * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic elements, chemical elements that are not naturally found on Earth and therefore have to be created in ...
acetylated analogue of psilocin and is a
prodrug A prodrug is a pharmacologically inactive medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be ...
of psilocin similarly to psilocybin. *
Mescaline Mescaline, also known as mescalin or mezcalin, and in chemical terms 3,4,5-trimethoxyphenethylamine, is a natural product, naturally occurring psychedelic drug, psychedelic alkaloid, protoalkaloid of the substituted phenethylamine class, found ...
(3,4,5-trimethoxyphenethylamine) is a
phenethylamine Phenethylamine (PEA) is an organic compound, natural monoamine alkaloid, and trace amine, which acts as a central nervous system stimulant in humans. In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace ami ...
alkaloid found in various species of cacti, the best-known of these being
peyote The peyote (; ''Lophophora williamsii'' ) is a small, spineless cactus which contains psychoactive alkaloids, particularly mescaline. is a Spanish word derived from the Nahuatl (), meaning "caterpillar cocoon", from a root , "to glisten". p. ...
(''Lophophora williamsii'') and the San Pedro cactus (''Trichocereus macrogonus'' var. ''pachanoi'', syn. ''Echinopsis pachanoi''). Mescaline has effects comparable to those of LSD and psilocybin. Ceremonial San Pedro use seems to be characterized by relatively strong spiritual experiences, and low incidence of challenging experiences. * DMT (''N'',''N''-dimethyltryptamine) is an
indole alkaloid Indole alkaloids are a class of alkaloids containing a structural moiety of indole; many indole alkaloids also include isoprene groups and are thus called terpene indole or secologanin tryptamine alkaloids. Containing more than 4100 known differ ...
found in various species of plants. Traditionally, it is consumed by tribes in
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
in the form of
ayahuasca AyahuascaPronounced as in the UK and in the US. Also occasionally known in English as ''ayaguasca'' (Spanish-derived), ''aioasca'' (Brazilian Portuguese-derived), or as ''yagé'', pronounced or . Etymologically, all forms but ''yagé'' descen ...
. A brew is used that consists of DMT-containing plants as well as plants containing MAOIs, specifically harmaline, which allows DMT to be consumed orally without being rendered inactive by
monoamine oxidase Monoamine oxidases (MAO) () are a family of enzymes that catalyze the oxidation of monoamines, employing oxygen to clip off their amine group. They are found bound to the outer membrane of mitochondria in most cell types of the body. The fi ...
enzymes in the digestive system. A pharmaceutical version of ayahuasca is called pharmahuasca. In the Western world, DMT is more commonly consumed via the vaporisation of freebase DMT. Whereas ayahuasca typically lasts for several hours, inhalation has an onset measured in seconds and has effects measured in minutes, being much more intense. Particularly in vaporised form, DMT has the ability to cause users to enter a hallucinatory realm fully detached from reality, being typically characterised by
hyperbolic geometry In mathematics, hyperbolic geometry (also called Lobachevskian geometry or János Bolyai, Bolyai–Nikolai Lobachevsky, Lobachevskian geometry) is a non-Euclidean geometry. The parallel postulate of Euclidean geometry is replaced with: :For a ...
, and described as defying visual or verbal description. Users have also reported encountering and communicating with entities within this hallucinatory state. DMT is the archetypal
substituted tryptamine Substituted tryptamines, or simply tryptamines, also known as serotonin analogues (i.e., 5-hydroxytryptamine analogues), are organic compounds which may be thought of as being derived from tryptamine itself. The molecular structures of all trypt ...
, being the structural scaffold of psilocybin and, to a lesser extent, the lysergamides. * 2C-B (2,5-dimethoxy-4-bromophenethylamine) is a
substituted phenethylamine Substituted phenethylamines (or simply phenethylamines) are a chemical class of organic compounds that are based upon the phenethylamine structure; the class is composed of all the derivative (chemistry), derivative compounds of phenethylamine ...
first synthesized in 1974 by
Alexander Shulgin Alexander Theodore "Sasha" Shulgin (June 17, 1925 – June 2, 2014) was an American biochemist, broad researcher of synthetic psychoactive compounds, and author of works regarding these, who independently explored the organic chemistry and ph ...
. 2C-B is both a psychedelic and a mild
entactogen Entactogens, also known as empathogens or connectogens, are a class of psychoactive drugs that induce the production of experiences of emotional communion, oneness, connectedness, emotional openness—that is, empathy—as particularly observe ...
, with its psychedelic effects increasing and its entactogenic effects decreasing with dosage. 2C-B is the most well-known compound in the 2C family, their general structure being discovered as a result of modifying the structure of mescaline. It is also the most widely used synthetic phenethylamine psychedelic.
MDMA 3,4-Methylenedioxymethamphetamine (MDMA), commonly known as ecstasy (tablet form), and molly (crystal form), is an empathogen–entactogenic drug with stimulant and minor Psychedelic drug, psychedelic properties. In studies, it has been used ...
("ecstasy") is sometimes said to also have weak psychedelic effects, but it acts and is classified mainly as an
entactogen Entactogens, also known as empathogens or connectogens, are a class of psychoactive drugs that induce the production of experiences of emotional communion, oneness, connectedness, emotional openness—that is, empathy—as particularly observe ...
rather than as a hallucinogen. Certain related drugs like MDA and MMDA have greater psychedelic effects however.


Uses


Recreational

Recreational use of psychedelics has been common since the psychedelic era of the mid-1960s and continues to play a role in various festivals and events, including
Burning Man Burning Man is a week-long large-scale desert event focused on "community, art, self-expression, and self-reliance" held annually in the Western United States. The event's name comes from its ceremony on the penultimate night of the event: the ...
. A survey published in 2013 found that 13.4% of American adults had used a psychedelic. A June 2024 report by the
RAND Corporation The RAND Corporation, doing business as RAND, is an American nonprofit global policy think tank, research institute, and public sector consulting firm. RAND engages in research and development (R&D) in several fields and industries. Since the ...
suggests psilocybin mushrooms may be the most prevalent psychedelic drug among adults in the United States. The RAND national survey indicated that 3.1% of U.S. adults reported using psilocybin in the past year. Roughly 12% of respondents acknowledged lifetime use of psilocybin, while a similar percentage reported having used
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
at some point in their lives.
MDMA 3,4-Methylenedioxymethamphetamine (MDMA), commonly known as ecstasy (tablet form), and molly (crystal form), is an empathogen–entactogenic drug with stimulant and minor Psychedelic drug, psychedelic properties. In studies, it has been used ...
, also known as ecstasy, showed a lower prevalence of use at 7.6%. Notably, less than 1% of U.S. adults reported using any psychedelic drugs within the past month.


Traditional

A number of frequently mentioned or traditional psychedelics such as ''
Ayahuasca AyahuascaPronounced as in the UK and in the US. Also occasionally known in English as ''ayaguasca'' (Spanish-derived), ''aioasca'' (Brazilian Portuguese-derived), or as ''yagé'', pronounced or . Etymologically, all forms but ''yagé'' descen ...
'' (which contains DMT), San Pedro,
Peyote The peyote (; ''Lophophora williamsii'' ) is a small, spineless cactus which contains psychoactive alkaloids, particularly mescaline. is a Spanish word derived from the Nahuatl (), meaning "caterpillar cocoon", from a root , "to glisten". p. ...
, and Peruvian torch (which all contain
mescaline Mescaline, also known as mescalin or mezcalin, and in chemical terms 3,4,5-trimethoxyphenethylamine, is a natural product, naturally occurring psychedelic drug, psychedelic alkaloid, protoalkaloid of the substituted phenethylamine class, found ...
), Psilocybe mushrooms (which contain
psilocin Psilocin, also known as 4-hydroxy-''N'',''N''-dimethyltryptamine (4-HO-DMT), is a substituted tryptamine alkaloid and a serotonergic psychedelic. It is present in most psychedelic mushrooms together with its phosphorylated counterpart psilocy ...
/
psilocybin Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
) and '' Tabernanthe iboga'' (which contains the unique psychedelic
ibogaine Ibogaine is a psychoactive indole alkaloid derived from plants such as '' Tabernanthe iboga'', characterized by hallucinogenic and oneirogenic effects. Traditionally used by Central African foragers, it has undergone controversial research ...
) all have a long and extensive history of spiritual,
shamanic Shamanism is a spiritual practice that involves a practitioner (shaman) interacting with the spirit world through Altered state of consciousness, altered states of consciousness, such as trance. The goal of this is usually to direct spiri ...
and traditional usage by
indigenous peoples There is no generally accepted definition of Indigenous peoples, although in the 21st century the focus has been on self-identification, cultural difference from other groups in a state, a special relationship with their traditional territ ...
in various world regions, particularly in Latin America, but also
Gabon Gabon ( ; ), officially the Gabonese Republic (), is a country on the Atlantic coast of Central Africa, on the equator, bordered by Equatorial Guinea to the northwest, Cameroon to the north, the Republic of the Congo to the east and south, and ...
, Africa in the case of iboga. Different countries and/or regions have come to be associated with traditional or spiritual use of particular psychedelics, such as the ancient and entheogenic use of psilocybe mushrooms by the native Mazatec people of
Oaxaca Oaxaca, officially the Free and Sovereign State of Oaxaca, is one of the 32 states that compose the political divisions of Mexico, Federative Entities of the Mexico, United Mexican States. It is divided into municipalities of Oaxaca, 570 munici ...
, Mexico or the use of the ayahuasca brew in the
Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributary, tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries ...
, particularly in Peru for spiritual and physical healing as well as for religious festivals. Peyote has also been used for several thousand years in the Rio Grande Valley in North America by native tribes as an
entheogen Entheogens are psychoactive substances used in spiritual and religious contexts to induce altered states of consciousness. Hallucinogens such as the psilocybin found in so-called "magic" mushrooms have been used in sacred contexts since ancie ...
. In the
Andean The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long and wide (widest between 18°S ...
region of South America, the San Pedro cactus ( ''Trichocereus macrogonus'' var. ''pachanoi'', syn. ''
Echinopsis pachanoi ''Trichocereus macrogonus'' var. ''pachanoi'' (Synonym (taxonomy), synonyms including ''Trichocereus pachanoi'' and ''Echinopsis pachanoi'') is a fast-growing columnar cactus found in the Andes at in altitude. It is one of a number of kinds of ...
'') has a long history of use, possibly as a
traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) refers to the knowledge, skills, and practices rooted in the cultural beliefs of various societies, especially Indigenous groups, used for maintaining health and treatin ...
. Archaeological studies have found evidence of use going back two thousand years, to Moche culture,
Nazca culture The Nazca culture (also Nasca) was the archaeological culture that flourished from beside the arid, southern coast of Peru in the river valleys of the Nazca, Rio Grande de Nazca drainage and the Ica Valley.''The Nasca'' by Helaine Silverman an ...
, and
Chavín culture The Chavín culture was a Pre-Columbian era, pre-Columbian civilization, developed in the northern Andean highlands of Peru around 900 BCE, ending around 250 BCE. It extended its influence to other civilizations along the Peruvian coast.Burger, R ...
. Although authorities of the
Roman Catholic The Catholic Church (), also known as the Roman Catholic Church, is the largest Christian church, with 1.27 to 1.41 billion baptized Catholics worldwide as of 2025. It is among the world's oldest and largest international institut ...
church attempted to suppress its use after the Spanish conquest, this failed, as shown by the Christian element in the common name "San Pedro cactus" –
Saint Peter Saint Peter (born Shimon Bar Yonah; 1 BC – AD 64/68), also known as Peter the Apostle, Simon Peter, Simeon, Simon, or Cephas, was one of the Twelve Apostles of Jesus and one of the first leaders of the Jewish Christian#Jerusalem ekklēsia, e ...
cactus. The name has its origin in the belief that just as St Peter holds the keys to heaven, the effects of the cactus allow users "to reach heaven while still on earth." In 2022, the Peruvian Ministry of Culture declared the traditional use of San Pedro cactus in northern Peru as
cultural heritage Cultural heritage is the heritage of tangible and intangible heritage assets of a group or society that is inherited from past generations. Not all heritages of past generations are "heritage"; rather, heritage is a product of selection by socie ...
. Although people of
Western culture Western culture, also known as Western civilization, European civilization, Occidental culture, Western society, or simply the West, refers to the Cultural heritage, internally diverse culture of the Western world. The term "Western" encompas ...
have tended to use psychedelics for either psychotherapeutic or recreational reasons, most indigenous cultures, particularly in South America, have seemingly tended to use psychedelics for more
supernatural Supernatural phenomena or entities are those beyond the Scientific law, laws of nature. The term is derived from Medieval Latin , from Latin 'above, beyond, outside of' + 'nature'. Although the corollary term "nature" has had multiple meanin ...
reasons such as
divination Divination () is the attempt to gain insight into a question or situation by way of an occultic ritual or practice. Using various methods throughout history, diviners ascertain their interpretations of how a should proceed by reading signs, ...
. This can often be related to "healing" or health as well but typically in the context of finding out what is wrong with the individual, such as using psychedelic states to "identify" a disease and/or its cause, locate lost objects, and identify a victim or even perpetrator of
sorcery Sorcery commonly refers to: * Magic (supernatural), the application of beliefs, rituals or actions employed to manipulate natural or supernatural beings and forces ** Goetia, ''Goetia'', magic involving the evocation of spirits ** Witchcraft, the ...
. In some cultures and regions, even psychedelics themselves, such as ayahuasca and the psychedelic
lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...
of eastern Ecuador ('' Dictyonema huaorani'') that supposedly contains both
5-MeO-DMT 5-MeO-DMT (5-methoxy-''N'',''N''-dimethyltryptamine), also known as ''O''-methylbufotenin or mebufotenin (), is a naturally occurring psychedelic of the tryptamine family. It is found in a wide variety of plant species, and is also secreted by ...
and psilocybin, have also been used by witches and sorcerers to conduct their malicious magic, similarly to
nightshade Solanaceae (), commonly known as the nightshades, is a family of flowering plants in the order Solanales. It contains approximately 2,700 species, several of which are used as agricultural crops, medicinal plants, and ornamental plants. Many me ...
deliriants Deliriants are a subclass of hallucinogen. The term was coined in the early 1980s to distinguish these drugs from psychedelics such as LSD and dissociatives such as ketamine, due to their primary effect of causing delirium, as opposed to t ...
like ''
brugmansia ''Brugmansia'' is a genus of seven species of flowering plants in the nightshade family Solanaceae. They are woody trees or shrubs, with pendulous flowers, and have no spines on their fruit. Their large, fragrant flowers give them their common n ...
'' and '' latua''.


Medical

Psychedelic therapy (or psychedelic-assisted therapy) is the proposed use of psychedelic drugs to treat
mental disorder A mental disorder, also referred to as a mental illness, a mental health condition, or a psychiatric disability, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. A mental disorder is ...
s. As of 2021, psychedelic drugs are controlled substances in most countries and psychedelic therapy is not legally available outside clinical trials, with some exceptions. The procedure for psychedelic therapy differs from that of therapies using conventional
psychiatric medication A psychiatric or psychotropic medication is a psychoactive drug taken to exert an effect on the chemical makeup of the brain and nervous system. Thus, these medications are used to treat mental illnesses. These medications are typically made of ...
s. While conventional medications are usually taken without supervision at least once daily, in contemporary psychedelic therapy the drug is administered in a single session (or sometimes up to three sessions) in a therapeutic context. The therapeutic team prepares the patient for the experience beforehand and helps them integrate insights from the drug experience afterwards. After ingesting the drug, the patient normally wears eyeshades and listens to music to facilitate focus on the psychedelic experience, with the therapeutic team interrupting only to provide reassurance if adverse effects such as anxiety or disorientation arise. As of 2022, the body of high-quality evidence on psychedelic therapy remains relatively small and more, larger studies are needed to reliably show the effectiveness and safety of psychedelic therapy's various forms and applications. On the basis of favorable early results, ongoing research is examining proposed psychedelic therapies for conditions including
major depressive disorder Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive depression (mood), low mood, low self-esteem, and anhedonia, loss of interest or pleasure in normally ...
, and
anxiety Anxiety is an emotion characterised by an unpleasant state of inner wikt:turmoil, turmoil and includes feelings of dread over Anticipation, anticipated events. Anxiety is different from fear in that fear is defined as the emotional response ...
and depression linked to
terminal illness Terminal illness or end-stage disease is a disease that cannot be cured or adequately treated and is expected to result in the death of the patient. This term is more commonly used for progressive diseases such as cancer, rather than fatal injur ...
. The United States
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...
has granted breakthrough therapy status, which expedites the assessment of promising drug therapies for potential approval, to psilocybin therapy for treatment-resistant depression and major depressive disorder. It has been proposed that psychedelics used for therapeutic purposes may act as active "super
placebo A placebo ( ) can be roughly defined as a sham medical treatment. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. Placebos are used in randomized clinical trials ...
s".


Microdosing

Psychedelic microdosing is the practice of using sub-threshold doses ( microdoses) of psychedelics in an attempt to improve creativity, boost physical energy level, emotional balance, increase performance on problems-solving tasks and to treat anxiety, depression and addiction. The practice of microdosing has become more widespread in the 21st century with more people claiming long-term benefits from the practice. A 2022 study recognized signatures of psilocybin microdosing in
natural language A natural language or ordinary language is a language that occurs naturally in a human community by a process of use, repetition, and change. It can take different forms, typically either a spoken language or a sign language. Natural languages ...
and concluded that low amount of psychedelics have potential for application, and ecological observation of microdosing schedules.


Dosage

The table below provides doses of major serotonergic psychedelics as well as the
entactogen Entactogens, also known as empathogens or connectogens, are a class of psychoactive drugs that induce the production of experiences of emotional communion, oneness, connectedness, emotional openness—that is, empathy—as particularly observe ...
and mild psychedelic
MDMA 3,4-Methylenedioxymethamphetamine (MDMA), commonly known as ecstasy (tablet form), and molly (crystal form), is an empathogen–entactogenic drug with stimulant and minor Psychedelic drug, psychedelic properties. In studies, it has been used ...
("ecstasy") that have been determined on the basis of
clinical studies Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietar ...
. Other dosage schemes have also been reported. In the case of dried psilocybin-containing mushrooms, microdoses are 0.1g to 0.3g and psychedelic doses are 1.0g to 3.5–5.0g. The preceding 1.0 to 5.0g range corresponds to psilocybin doses of about 10 to 50mg. Psilocybin-containing mushrooms vary in their psilocybin and
psilocin Psilocin, also known as 4-hydroxy-''N'',''N''-dimethyltryptamine (4-HO-DMT), is a substituted tryptamine alkaloid and a serotonergic psychedelic. It is present in most psychedelic mushrooms together with its phosphorylated counterpart psilocy ...
content, but are typically around 1% of the dried weight of the mushrooms (in terms of total or combined psilocybin and psilocin content). Psilocybin and psilocin are similar in potency and dose but psilocin is about 1.4-fold more active, this being related to the difference in
molecular weight A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...
between the two compounds. Some psychedelics, such as 2C-B,
2C-E 2C-E is a Psychedelic drug, psychedelic phenethylamines, phenethylamine of the 2C (psychedelics), 2C family. It was first synthesized by Alexander Shulgin and documented in his book ''PiHKAL''. Like the other substances in its family, it produces ...
, and 4-HO-DiPT, have been said to have steep dose–response curves, meaning that the difference in dose between a light experience and an overwhelming disconnection from reality can be small.


Effects


Psychedelic effects

Although several attempts have been made, starting in the 19th and 20th centuries, to define common phenomenological structures of the effects produced by classic psychedelics, a universally accepted taxonomy does not yet exist. At lower doses, features of psychedelic experiences include sensory alterations, such as the warping of surfaces, shape suggestibility,
pareidolia Pareidolia (; ) is the tendency for perception to impose a meaningful interpretation on a nebulous stimulus (physiology), stimulus, usually visual, so that one detects an object, pattern, or meaning where there is none. Pareidolia is a specific bu ...
, and color variations. Users often report intense colors that they have not previously experienced, and repetitive geometric shapes or
form constants A form constant is one of several Pattern, geometric patterns which are recurringly observed during hypnagogia, hallucinations and altered states of consciousness. History In 1926, Heinrich Klüver systematically studied the effects of mescalin ...
are common as well. Higher doses often cause intense and fundamental alterations of sensory (notably
visual The visual system is the physiological basis of visual perception (the ability to detect and process light). The system detects, transduces and interprets information concerning light within the visible range to construct an image and buil ...
) perception, such as
synesthesia Synesthesia (American English) or synaesthesia (British English) is a perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathway. People with sy ...
or the experience of additional spatial or temporal dimensions. Tryptamines are well documented to cause classic psychedelic states, such as increased
empathy Empathy is generally described as the ability to take on another person's perspective, to understand, feel, and possibly share and respond to their experience. There are more (sometimes conflicting) definitions of empathy that include but are ...
, visual distortions (drifting, morphing, breathing, melting of various surfaces and objects), auditory hallucinations, ego dissolution or
ego death Ego death is a "complete loss of subjective self-identity". The term is used in various intertwined contexts, with related meanings. The 19th-century philosopher and psychologist William James uses the synonymous term "self-surrender", and Jung ...
with high enough dose, mystical,
transpersonal The transpersonal is a term used by different schools of philosophy and psychology in order to describe experiences and worldviews that extend beyond the personal level of the psyche, and beyond mundane worldly events. Definition and context The ...
and spiritual experiences, autonomous "
entity An entity is something that Existence, exists as itself. It does not need to be of material existence. In particular, abstractions and legal fictions are usually regarded as entities. In general, there is also no presumption that an entity is Lif ...
" encounters, time distortion, closed eye hallucinations and complete detachment from reality with a high enough dose. Luis Luna describes psychedelic experiences as having a distinctly
gnosis Gnosis is the common Greek noun for knowledge ( γνῶσις, ''gnōsis'', f.). The term was used among various Hellenistic religions and philosophies in the Greco-Roman world. It is best known for its implication within Gnosticism, where ...
-like quality, and says that they offer "learning experiences that elevate consciousness and can make a profound contribution to
personal development Personal development or self-improvement consists of activities that develops a person's capabilities and potential, enhance quality of life, and facilitate the realization of dreams and aspirations. Personal development may take place over the ...
." Czech psychiatrist
Stanislav Grof Stanislav Grof (born July 1, 1931) is a Czech-born American psychiatrist. Grof is one of the principal developers of transpersonal psychology and research into the use of non-ordinary states of consciousness for purposes of psychological hea ...
studied the effects of psychedelics like LSD early in his career and said of the experience, that it commonly includes "complex revelatory insights into the nature of existence… typically accompanied by a sense of certainty that this knowledge is ultimately more relevant and 'real' than the perceptions and beliefs we share in everyday life." Traditionally, the standard model for the subjective phenomenological effects of psychedelics has typically been based on LSD, with anything that is considered "psychedelic" evidently being compared to it and its specific effects. Good trips are reportedly deeply pleasurable, and typically involve intense joy or euphoria, a greater appreciation for life, reduced anxiety, a sense of spiritual enlightenment, and a sense of belonging or interconnectedness with the universe. Negative experiences, colloquially known as "bad trips," evoke an array of dark emotions, such as irrational fear, anxiety, panic, paranoia, dread, distrustfulness, hopelessness, and even suicidal ideation. While it is impossible to predict when a bad trip will occur, one's mood, surroundings, sleep, hydration, social setting, and other factors can be controlled (colloquially referred to as " set and setting") to minimize the risk of a bad trip. The concept of "set and setting" also generally appears to be more applicable to psychedelics than to other types of hallucinogens such as deliriants, hypnotics and dissociative anesthetics. Psychedelics include
naturally occurring A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical ...
tryptamine Tryptamine is an indolamine metabolite of the essential amino acid tryptophan. The chemical structure is defined by an indole—a fused benzene and pyrrole ring, and a 2-aminoethyl group at the second carbon (third aromatic atom, with the firs ...
s like
psilocybin Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
and DMT, the naturally occurring
phenethylamine Phenethylamine (PEA) is an organic compound, natural monoamine alkaloid, and trace amine, which acts as a central nervous system stimulant in humans. In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace ami ...
mescaline Mescaline, also known as mescalin or mezcalin, and in chemical terms 3,4,5-trimethoxyphenethylamine, is a natural product, naturally occurring psychedelic drug, psychedelic alkaloid, protoalkaloid of the substituted phenethylamine class, found ...
, and naturally occurring lysergamides like
ergine Ergine, also known as lysergic acid amide (LSA or LAA) as well as LA-111, is a psychoactive compound of the ergoline and lysergamide families related to lysergic acid diethylamide (LSD). Ergine is an ergoline alkaloid found in fungi such as ...
(lysergic acid amide; LSA), as well as
synthetic Synthetic may refer to: Science * Synthetic biology * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic elements, chemical elements that are not naturally found on Earth and therefore have to be created in ...
analogues and
derivative In mathematics, the derivative is a fundamental tool that quantifies the sensitivity to change of a function's output with respect to its input. The derivative of a function of a single variable at a chosen input value, when it exists, is t ...
s like
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
and 2C-B. Many of these psychedelics cause remarkably similar effects, despite their different
chemical structure A chemical structure of a molecule is a spatial arrangement of its atoms and their chemical bonds. Its determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target m ...
s. However, many users anecdotally report that the three major families have subjectively different qualities in the "feel" of the experience, which are difficult to describe. There can also be very substantial differences between the drugs; for instance,
5-MeO-DMT 5-MeO-DMT (5-methoxy-''N'',''N''-dimethyltryptamine), also known as ''O''-methylbufotenin or mebufotenin (), is a naturally occurring psychedelic of the tryptamine family. It is found in a wide variety of plant species, and is also secreted by ...
rarely produces the visual effects typical of other psychedelics. As additional examples, DiPT is said to primarily affect the auditory sense, 2C-T-17 and ASR-3001 (5-MeO-iPALT) are said to produce psychedelic effects on thinking or "head space" with few or no visuals, and ''N''-methyltryptamine (NMT) has been said to be a primarily spatial psychedelic. The visuals of psychedelics have been reproduced in video and image form using
artificial intelligence Artificial intelligence (AI) is the capability of computer, computational systems to perform tasks typically associated with human intelligence, such as learning, reasoning, problem-solving, perception, and decision-making. It is a field of re ...
. Some rare individuals do not experience hallucinogenic effects with serotonergic psychedelics.


Other psychoactive effects

Some psychedelics have been associated with other
psychoactive A psychoactive drug, psychopharmaceutical, mind-altering drug, consciousness-altering drug, psychoactive substance, or psychotropic substance is a chemical substance that alters psychological functioning by modulating central nervous system acti ...
effects in addition to their hallucinogenic effects. For example, psychedelics like
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
and DOM have been described as having mild
stimulant Stimulants (also known as central nervous system stimulants, or psychostimulants, or colloquially as uppers) are a class of drugs that increase alertness. They are used for various purposes, such as enhancing attention, motivation, cognition, ...
and/or " psychic-energizing" (i.e., acute
antidepressant Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction. Common side effects of antidepressants include Xerostomia, dry mouth, weight gain, dizziness, headaches, akathi ...
) effects. Some psychedelics and related drugs, like DOET (low doses),
Ariadne In Greek mythology, Ariadne (; ; ) was a Cretan princess, the daughter of King Minos of Crete. There are variations of Ariadne's myth, but she is known for helping Theseus escape from the Minotaur and being abandoned by him on the island of N ...
, and ASR-2001 (2CB-5PrO), have been investigated specifically for such effects. 2C-B has been said to have mild
entactogen Entactogens, also known as empathogens or connectogens, are a class of psychoactive drugs that induce the production of experiences of emotional communion, oneness, connectedness, emotional openness—that is, empathy—as particularly observe ...
ic effects at low doses. Some drugs, such as MDxx compounds like
MDMA 3,4-Methylenedioxymethamphetamine (MDMA), commonly known as ecstasy (tablet form), and molly (crystal form), is an empathogen–entactogenic drug with stimulant and minor Psychedelic drug, psychedelic properties. In studies, it has been used ...
and MDA as well as α-alkyltryptamines like α-methyltryptamine (AMT), are entactogens and/or stimulants acting at
monoamine transporter Monoamine transporters (MATs) are proteins that function as integral Cell membrane, plasma-membrane Neurotransmitter transporter, transporters to regulate concentrations of extracellular monoamine neurotransmitters. The three major classes are se ...
s in addition to having varying degrees of psychedelic effects.


Psychedelic afterglows

Psychedelics are associated with an
afterglow An afterglow in meteorology consists of several atmospheric optical phenomena, with a general definition as a broad arch of whitish or pinkish sunlight in the twilight sky, consisting of the bright segment and the purple light. Purple light mai ...
, also known as positive subacute or post-experience effects, which may last days or even weeks after the psychedelic experience. These effects include reduction in
psychopathology Psychopathology is the study of mental illness. It includes the signs and symptoms of all mental disorders. The field includes Abnormal psychology, abnormal cognition, maladaptive behavior, and experiences which differ according to social norms ...
and increased
well-being Well-being is what is Intrinsic value (ethics), ultimately good for a person. Also called "welfare" and "quality of life", it is a measure of how well life is going for someone. It is a central goal of many individual and societal endeavors. ...
, mood,
mindfulness Mindfulness is the cognitive skill, usually developed through exercises, of sustaining metacognitive awareness towards the contents of one's own mind and bodily sensations in the present moment. The term ''mindfulness'' derives from the Pali ...
, social functioning,
spirituality The meaning of ''spirituality'' has developed and expanded over time, and various meanings can be found alongside each other. Traditionally, spirituality referred to a religious process of re-formation which "aims to recover the original shape o ...
, and
executive function In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that support goal-directed behavior, by regulating thoughts and actions thro ...
ing, and positive behavioral changes. They also include mixed changes in
personality Personality is any person's collection of interrelated behavioral, cognitive, and emotional patterns that comprise a person’s unique adjustment to life. These interrelated patterns are relatively stable, but can change over long time per ...
,
values In ethics and social sciences, value denotes the degree of importance of some thing or action, with the aim of determining which actions are best to do or what way is best to live ( normative ethics), or to describe the significance of different a ...
,
attitude Attitude or Attitude may refer to: Philosophy and psychology * Attitude (psychology), a disposition or state of mind ** Attitude change * Propositional attitude, a mental state held towards a proposition Science and technology * Orientation ...
s,
creativity Creativity is the ability to form novel and valuable Idea, ideas or works using one's imagination. Products of creativity may be intangible (e.g. an idea, scientific theory, Literature, literary work, musical composition, or joke), or a physica ...
, and
flexibility Stiffness is the extent to which an object resists deformation in response to an applied force. The complementary concept is flexibility or pliability: the more flexible an object is, the less stiff it is. Calculations The stiffness, k, of a ...
, as well as
adverse effect An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term compli ...
s like
headache A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of Depression (mood), depression in those with severe ...
s, sleep disturbances, and sometimes increased
psychological distress Mental distress or psychological distress encompasses the symptoms and experiences of a person's internal life that are commonly held to be troubling, confusing or out of the ordinary. Mental distress can potentially lead to a change of behavior, ...
. The afterglow period has been associated with changes in
brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...
function,
neuroplasticity Neuroplasticity, also known as neural plasticity or just plasticity, is the ability of neural networks in the brain to change through neurogenesis, growth and reorganization. Neuroplasticity refers to the brain's ability to reorganize and rewir ...
, and
immune system The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
function. Both
psychological Psychology is the scientific study of mind and behavior. Its subject matter includes the behavior of humans and nonhumans, both consciousness, conscious and Unconscious mind, unconscious phenomena, and mental processes such as thoughts, feel ...
and
pharmacological Pharmacology is the science of drugs and medications, including a substance's origin, composition, pharmacokinetics, pharmacodynamics, therapeutic use, and toxicology. More specifically, it is the study of the interactions that occur between ...
effects may be involved in the afterglow phenomenon. In 1898, the English writer and intellectual
Havelock Ellis Henry Havelock Ellis (2 February 1859 – 8 July 1939) was an English physician, eugenicist, writer, Progressivism, progressive intellectual and social reformer who studied human sexuality. He co-wrote the first medical textbook in English on h ...
reported a heightened perceptual sensitivity to "the more delicate phenomena of light and shade and color" for a prolonged period of time after his exposure to mescaline. The term "psychedelic afterglow" was first formally coined in the 1960s. Albert Hofmann, the discoverer of LSD, said the following about the aftermath of his first full LSD experience in his 1980 book ''LSD: My Problem Child'': During a speech on his 100th birthday in 2006, Hofmann additionally said of LSD:


Adverse effects

Despite the contrary perception of much of the public, psychedelic drugs are not addictive and are physiologically
safe A safe (also called a strongbox or coffer) is a secure lockable enclosure used for securing valuable objects against theft or fire. A safe is usually a hollow cuboid or cylinder, with one face being removable or hinged to form a door. The body ...
. Risks do exist during an unsupervised psychedelic experience, however; Ira Byock wrote in 2018 in the '' Journal of Palliative Medicine'' that psilocybin is safe when administered to a properly screened patient and supervised by a qualified professional with appropriate set and setting. However, he called for an "abundance of caution" because in the absence of these conditions a range of negative reactions is possible, including "fear, a prolonged sense of dread, or full panic." He notes that driving or even walking in public can be dangerous during a psychedelic experience because of impaired hand-eye coordination and fine motor control. In some cases, individuals taking psychedelics have performed dangerous or fatal acts because they believed they possessed superhuman powers. Psilocybin-induced states of mind share features with states experienced in
psychosis In psychopathology, psychosis is a condition in which a person is unable to distinguish, in their experience of life, between what is and is not real. Examples of psychotic symptoms are delusions, hallucinations, and disorganized or inco ...
, and while a causal relationship between psilocybin and the onset of psychosis has not been established as of 2011, researchers have called for investigation of the relationship. Many of the persistent negative perceptions of psychological risks are unsupported by the currently available scientific evidence, with the majority of reported adverse effects not being observed in a regulated and/or medical context. A population study on associations between psychedelic use and mental illness published in 2013 found no evidence that psychedelic use was associated with increased prevalence of any mental illness. In any case, induction of psychosis has been associated with psychedelics in small percentages of individuals, and the rates appear to be higher in people with
schizophrenia Schizophrenia () is a mental disorder characterized variously by hallucinations (typically, Auditory hallucination#Schizophrenia, hearing voices), delusions, thought disorder, disorganized thinking and behavior, and Reduced affect display, f ...
. Using psychedelics poses certain risks of re-experiencing of the drug's effects, including flashbacks and
hallucinogen persisting perception disorder Hallucinogen persisting perception disorder (HPPD) is a non-psychotic disorder in which a person experiences apparent lasting or persistent visual hallucinations or perceptual distortions after using drugs, including but not limited to psychedeli ...
(HPPD). These non-psychotic effects are poorly studied, but the permanent symptoms (also called "endless trip") are considered to be rare. Serotonergic psychedelics are
agonist An agonist is a chemical that activates a Receptor (biochemistry), receptor to produce a biological response. Receptors are Cell (biology), cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an R ...
s not only of the
serotonin Serotonin (), also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter with a wide range of functions in both the central nervous system (CNS) and also peripheral tissues. It is involved in mood, cognition, reward, learning, ...
5-HT2A receptor but also of the serotonin 5-HT2B receptor and other
serotonin receptor 5-HT receptors, 5-hydroxytryptamine receptors, or serotonin receptors, are a group of G protein-coupled receptor and ligand-gated ion channels found in multiple tissues including the central and peripheral nervous systems. They mediate both ex ...
s. A potential risk of frequent repeated use of serotonergic psychedelics is cardiac fibrosis and valvulopathy caused by serotonin 5-HT2B receptor activation. However, single high doses or widely spaced doses (e.g., months) are widely thought to be safe and concerns about cardiac toxicity apply more to chronic
psychedelic microdosing Psychedelic microdosing is a form of microdosing, drug microdosing in which sub-hallucinogenic doses of serotonergic psychedelics like LSD and psilocybin are taken for claimed cognitive and emotional benefits. Uses, research, and effects A vari ...
or very frequent use (e.g., weekly). Selective serotonin 5-HT2A receptor agonists that do not activate the serotonin 5-HT2B receptor or other serotonin receptors, such as
25CN-NBOH 25CN-NBOH, also known as NBOH-2C-CN, is a compound indirectly derived from the phenethylamine series of hallucinogens, which was discovered in 2014 at the University of Copenhagen. It is a member of the NBOMe family of psychedelic drug, psychedel ...
, DMBMPP, and LPH-5, have been developed and are being studied. Selective serotonin 5-HT2A receptor agonists are expected to avoid the cardiac risks of serotonin 5-HT2B receptor activation.


Overdose

There have been a handful of cases of fatal
overdose A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended. Retrieved on September 20, 2014.
with
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
,
psilocybin Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
, and
mescaline Mescaline, also known as mescalin or mezcalin, and in chemical terms 3,4,5-trimethoxyphenethylamine, is a natural product, naturally occurring psychedelic drug, psychedelic alkaloid, protoalkaloid of the substituted phenethylamine class, found ...
. There have also been cases of death with
dimethyltryptamine Dimethyltryptamine (DMT), also known as ''N'',''N''-dimethyltryptamine (''N'',''N''-DMT), is a Psychedelic drug, serotonergic hallucinogen and Investigational New Drug, investigational drug of the substituted tryptamine, tryptamine family tha ...
(DMT),
5-MeO-DMT 5-MeO-DMT (5-methoxy-''N'',''N''-dimethyltryptamine), also known as ''O''-methylbufotenin or mebufotenin (), is a naturally occurring psychedelic of the tryptamine family. It is found in a wide variety of plant species, and is also secreted by ...
, 2C-B, Bromo-DragonFLY,
NBOMe The 25-NB (25''x''-NB''x'') series, or NBOMe series, also known as the ''N''-benzylphenethylamines, is a family of serotonergic psychedelics. They are substituted phenethylamines and were derived from the 2C (psychedelics), 2C family. The most c ...
s like
25I-NBOMe 25I-NBOMe, also known as 2C-I-NBOMe, Cimbi-5, and shortened to "25I", is a psychedelic drug of the phenethylamine, 2C, and NBOMe (25-NB) families. Since 2010, it has circulated in the recreational drug scene, often misrepresented as LSD. It is ...
, and other psychedelics. LSD and psilocybin appear to have very wide margins of safety with overdose, whereas mescaline and 2C-B have much narrower margins, and NBOMes appear to be especially
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
and uniquely linked to
serotonin syndrome Serotonin syndrome (SS) is a group of symptoms that may occur with the use of certain Serotonin, serotonergic medications or Recreational drug use, drugs. The symptoms can range from mild to severe, and are potentially fatal. Symptoms in mild c ...
-type symptoms. In terms of extrapolated human
lethal dose In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation. Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilog ...
s based on
animal studies Animal studies is a recently recognised field in which animals are studied in a variety of cross-disciplinary ways. Scholars who engage in animal studies may be formally trained in a number of diverse fields, including art history, anthropology ...
and human
case report In medicine, a case report is a detailed report of the symptoms, signs, diagnosis, treatment, and follow-up of an individual patient. Case reports may contain a demographic profile of the patient, but usually describe an unusual or novel occurrenc ...
s, lethal doses of psychedelics relative to typical recreational doses are estimated to be 1,000-fold for LSD, 200-fold for psilocybin, 50-fold for oral DMT (as
ayahuasca AyahuascaPronounced as in the UK and in the US. Also occasionally known in English as ''ayaguasca'' (Spanish-derived), ''aioasca'' (Brazilian Portuguese-derived), or as ''yagé'', pronounced or . Etymologically, all forms but ''yagé'' descen ...
), and 24-fold for mescaline. Estimates for other psychedelics, like 5-MeO-DMT and 2C-B, could not be made.


Interactions

Serotonin 5-HT2A receptor
antagonist An antagonist is a character in a story who is presented as the main enemy or rival of the protagonist and is often depicted as a villain. Numerous drugs act as serotonin 5-HT2A receptor antagonists, for instance
antidepressant Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction. Common side effects of antidepressants include Xerostomia, dry mouth, weight gain, dizziness, headaches, akathi ...
s like
trazodone Trazodone is an antidepressant medication used to treat major depressive disorder, anxiety disorders, and insomnia. It is a phenylpiperazine compound of the serotonin antagonist and reuptake inhibitor (SARI) class. The medication is taken or ...
and
mirtazapine Mirtazapine, sold under the brand name Remeron among others, is an atypical antidepressant, atypical tetracyclic antidepressant, and as such is used primarily to treat Depression (mood), depression. Its effects may take up to four weeks but ca ...
,
antipsychotic Antipsychotics, previously known as neuroleptics and major tranquilizers, are a class of Psychiatric medication, psychotropic medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought), p ...
s like quetiapine,
olanzapine Olanzapine, sold under the brand name Zyprexa among others, is an atypical antipsychotic primarily used to treat schizophrenia and bipolar disorder. It is also sometimes used off-label for treatment of chemotherapy-induced nausea and vomitin ...
, and
risperidone Risperidone, sold under the brand name Risperdal among others, is an atypical antipsychotic used to treat schizophrenia and bipolar disorder, as well as aggressive and self-injurious behaviors associated with autism spectrum disorder. It is t ...
, and other agents like
ketanserin Ketanserin, sold under the brand name Sufrexal, is an antihypertensive agent which is used to treat arterial hypertension and vasospasm, vasospastic disorders. It is also used in scientific research as an antiserotonergic medication, agent in th ...
, pimavanserin,
cyproheptadine Cyproheptadine, sold under the brand name Periactin among others, is a first-generation antihistamine, first-generation antihistamine with additional anticholinergic, antiserotonergic, and local anesthetic properties. It was patented in 1959 a ...
, and pizotifen. Such drugs are sometimes referred to as " trip killers" due to their ability to prevent or abort the hallucinogenic effects of psychedelics. Besides serotonin 5-HT2A receptor antagonists, non-hallucinogenic serotonin 5-HT2A receptor
partial agonist In pharmacology, partial agonists are drugs that bind to and activate a given Receptor (biochemistry), receptor, but have only partial Intrinsic activity, efficacy at the receptor relative to a full agonist. They may also be considered Ligand (bio ...
s, such as lisuride, may also block the hallucinogenic effects of serotonergic psychedelics. The serotonin 5-HT1A receptor
partial agonist In pharmacology, partial agonists are drugs that bind to and activate a given Receptor (biochemistry), receptor, but have only partial Intrinsic activity, efficacy at the receptor relative to a full agonist. They may also be considered Ligand (bio ...
buspirone Buspirone, sold under the brand name Buspar among others, is an anxiolytic, a medication primarily used to treat anxiety disorders, particularly generalized anxiety disorder (GAD). It is a serotonin 5-HT1A receptor, 5-HT1A receptor partial ag ...
has been found to markedly reduce the hallucinogenic effects of psilocybin in humans. Conversely, the serotonin 5-HT1A receptor antagonist pindolol has been found to potentiate the hallucinogenic effects of DMT by 2- to 3-fold in humans. Serotonin 5-HT1A receptor agonism may modify and self-inhibit the effects of psychedelics that possess this property. A particularly notable example is 5-methoxytryptamine
derivative In mathematics, the derivative is a fundamental tool that quantifies the sensitivity to change of a function's output with respect to its input. The derivative of a function of a single variable at a chosen input value, when it exists, is t ...
s such as
5-MeO-DMT 5-MeO-DMT (5-methoxy-''N'',''N''-dimethyltryptamine), also known as ''O''-methylbufotenin or mebufotenin (), is a naturally occurring psychedelic of the tryptamine family. It is found in a wide variety of plant species, and is also secreted by ...
, which are more potent serotonin 5-HT1A receptor agonists than other psychedelics and have qualitatively unique and differing hallucinogenic effects.
Benzodiazepine Benzodiazepines (BZD, BDZ, BZs), colloquially known as "benzos", are a class of central nervous system (CNS) depressant, depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed t ...
s, for example
diazepam Diazepam, sold under the brand name Valium among others, is a medicine of the benzodiazepine family that acts as an anxiolytic. It is used to treat a range of conditions, including anxiety disorder, anxiety, seizures, alcohol withdrawal syndr ...
,
alprazolam Alprazolam, sold under the brand name Xanax among others, is a fast-acting, potent tranquilizer of moderate duration within the triazolobenzodiazepine group of chemicals called benzodiazepines. Alprazolam is most commonly prescribed in the ...
,
clonazepam Clonazepam, sold under the brand name Klonopin among others, is a benzodiazepine medication used to prevent and treat anxiety disorders, seizures, bipolar mania, agitation associated with psychosis, obsessive–compulsive disorder (OCD), and ...
, and
lorazepam Lorazepam, sold under the brand name Ativan, Tavor among others, is a benzodiazepine medication. It is used to treat anxiety (including anxiety disorders), insomnia, severe agitation, active seizures including status epilepticus, alcoh ...
, as well as
alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...
, which act as GABAA receptor positive allosteric modulators, have been limitedly studied in combination with psychedelics and are not currently known to directly interact with them. However, these
GABAergic In molecular biology and physiology, something is GABAergic or GABAnergic if it pertains to or affects the neurotransmitter gamma-aminobutyric acid (GABA). For example, a synapse is GABAergic if it uses GABA as its neurotransmitter, and a GABAergic ...
drugs produce effects such as
anxiolysis An anxiolytic (; also antipanic or anti-anxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxie ...
,
sedation Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure. Examples of drugs which can be used for sedation include isoflurane, diethyl ether, ...
, and
amnesia Amnesia is a deficit in memory caused by brain damage or brain diseases,Gazzaniga, M., Ivry, R., & Mangun, G. (2009) Cognitive Neuroscience: The biology of the mind. New York: W.W. Norton & Company. but it can also be temporarily caused by t ...
, and in relation to this, may diminish or otherwise oppose the effects of psychedelics. As a result of this, benzodiazepines and alcohol are often used by recreational users as "trip killers" to manage difficult hallucinogenic experiences with psychedelics, for instance experiences with prominent anxiety. The
safety Safety is the state of being protected from harm or other danger. Safety can also refer to the control of recognized hazards in order to achieve an acceptable level of risk. Meanings The word 'safety' entered the English language in the 1 ...
of this strategy is not entirely clear and might have risks. However, benzodiazepines have been used clinically to manage the adverse psychological effects of psychedelics, for instance in clinical studies and in the
emergency department An emergency department (ED), also known as an accident and emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the Acute (medicine), ...
. A clinical trial of
psilocybin Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
and
midazolam Midazolam, sold under the brand name Versed among others, is a benzodiazepine medication used for anesthesia, premedication before surgical anesthesia, and procedural sedation, and to treat psychomotor agitation, severe agitation. It induces ...
coadministration found that midazolam clouded the effects of psilocybin and impaired memory of the experience. Benzodiazepines might interfere with the therapeutic effects of psychedelics, such as sustained
antidepressant Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction. Common side effects of antidepressants include Xerostomia, dry mouth, weight gain, dizziness, headaches, akathi ...
effects. Some serotonergic psychedelics, for instance
dimethyltryptamine Dimethyltryptamine (DMT), also known as ''N'',''N''-dimethyltryptamine (''N'',''N''-DMT), is a Psychedelic drug, serotonergic hallucinogen and Investigational New Drug, investigational drug of the substituted tryptamine, tryptamine family tha ...
(DMT) and
5-MeO-DMT 5-MeO-DMT (5-methoxy-''N'',''N''-dimethyltryptamine), also known as ''O''-methylbufotenin or mebufotenin (), is a naturally occurring psychedelic of the tryptamine family. It is found in a wide variety of plant species, and is also secreted by ...
, are highly susceptible
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...
s for
monoamine oxidase Monoamine oxidases (MAO) () are a family of enzymes that catalyze the oxidation of monoamines, employing oxygen to clip off their amine group. They are found bound to the outer membrane of mitochondria in most cell types of the body. The fi ...
(MAO), specifically
MAO-A Monoamine oxidase A, also known as MAO-A, is an enzyme ( E.C. 1.4.3.4) that in humans is encoded by the ''MAOA'' gene. This gene is one of two neighboring gene family members that encode mitochondrial enzymes which catalyze the oxidative deamin ...
, and hence can be greatly potentiated by
monoamine oxidase inhibitor Monoamine oxidase inhibitors (MAOIs) are a drug class, class of drugs that inhibit the activity of one or both monoamine oxidase enzymes: monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B). They are best known as effective antidepressa ...
s (MAOIs). An example of this is
ayahuasca AyahuascaPronounced as in the UK and in the US. Also occasionally known in English as ''ayaguasca'' (Spanish-derived), ''aioasca'' (Brazilian Portuguese-derived), or as ''yagé'', pronounced or . Etymologically, all forms but ''yagé'' descen ...
, in which plants containing both DMT and
harmala alkaloid Harmala alkaloids are several alkaloids that act as monoamine oxidase inhibitors (MAOIs). These alkaloids are found in the seeds of ''Peganum harmala'' (also known as harmal or Syrian rue), as well as ''Banisteriopsis caapi'' (ayahuasca), leave ...
s acting as MAOIs such as harmine and harmaline are combined. This allows DMT to become orally active and to have a much longer
duration of action Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms (fo ...
than usual. The 2C psychedelics, such as 2C-B,
2C-I 2C-I, also known as 2,5-dimethoxy-4-iodophenethylamine, is a phenethylamine of the 2C family with psychedelic effects. It was first synthesized by Alexander Shulgin, and is described in Shulgin's book ''PiHKAL'' (1991). The substance is con ...
, and
2C-E 2C-E is a Psychedelic drug, psychedelic phenethylamines, phenethylamine of the 2C (psychedelics), 2C family. It was first synthesized by Alexander Shulgin and documented in his book ''PiHKAL''. Like the other substances in its family, it produces ...
, are also substrates of both MAO-A and
MAO-B Monoamine oxidase B (MAO-B) is an enzyme that in humans is encoded by the ''MAOB'' gene. The protein encoded by this gene belongs to the flavin monoamine oxidase family. It is an enzyme located in the outer mitochondrial membrane. It catalyze ...
, and may likewise be greatly potentiated by MAOIs. Examples of MAOIs that may potentiate psychedelics behaving as MAO-A and/or MAO-B substrates include
phenelzine Phenelzine, sold under the brand name Nardil among others, is a non-selective and irreversible monoamine oxidase inhibitor (MAOI) of the hydrazine family which is primarily used as an antidepressant and anxiolytic to treat depression and a ...
,
tranylcypromine Tranylcypromine, sold under the brand name Parnate among others, is a monoamine oxidase inhibitor (MAOI). More specifically, tranylcypromine acts as nonselective and irreversible inhibitor of the enzyme monoamine oxidase (MAO). It is used a ...
, isocarboxazid,
moclobemide Moclobemide, sold under the brand names Amira, Aurorix, Clobemix, Depnil and Manerix among others, is a reversible inhibitor of monoamine oxidase A (RIMA) drug primarily used to treat Clinical depression, depression and social anxiety. It is not ...
, and
selegiline Selegiline, also known as L-deprenyl and sold under the brand names Eldepryl, Zelapar, and Emsam among others, is a medication which is used in the treatment of Parkinson's disease and major depressive disorder. It has also been studied and us ...
. Combination of MAO-substrate psychedelics with MAOIs can result in
overdose A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended. Retrieved on September 20, 2014.
and serious
toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...
, including death. Other psychedelics, such as
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
, are not substrates of MAO and are not potentiated by MAOIs. The extent to which
psilocin Psilocin, also known as 4-hydroxy-''N'',''N''-dimethyltryptamine (4-HO-DMT), is a substituted tryptamine alkaloid and a serotonergic psychedelic. It is present in most psychedelic mushrooms together with its phosphorylated counterpart psilocy ...
(and by extension
psilocybin Psilocybin, also known as 4-phosphoryloxy-''N'',''N''-dimethyltryptamine (4-PO-DMT), is a natural product, naturally occurring tryptamine alkaloid and Investigational New Drug, investigational drug found in more than List of psilocybin mushroom ...
) is metabolized by MAO, specifically MAO-A, is not fully clear, but has ranged from 4% to 33% in different studies based on
metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...
excretion Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, Kidney (vertebrates), kidneys, and skin. This is in contrast with secretion, where the substa ...
. However, circulating levels of the deaminated metabolite of psilocin are far higher than those of free unmetabolized psilocin with psilocybin administration. An early clinical study of psilocybin in combination with short-term tranylcypromine pretreatment found that tranylcypromine marginally potentiated the
peripheral A peripheral device, or simply peripheral, is an auxiliary hardware device that a computer uses to transfer information externally. A peripheral is a hardware component that is accessible to and controlled by a computer but is not a core compo ...
effects of psilocybin, including pressor effects and
mydriasis Mydriasis is the Pupillary dilation, dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response. Non-physiological causes of mydriasis include disease, Physical trauma, trauma, or the use of c ...
, but overall did not significantly modify the psychoactive and hallucinogenic effects of the psilocybin, although some of its emotional effects were said to be reduced and some of its perceptual effects were said to be amplified. Some psychedelics are substrates of
cytochrome P450 Cytochromes P450 (P450s or CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that mostly, but not exclusively, function as monooxygenases. However, they are not omnipresent; for examp ...
(CYP450)
enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
s, for instance LSD being a substrate of
CYP2D6 Cytochrome P450 2D6 (CYP2D6) is an enzyme that in humans is encoded by the ''CYP2D6'' gene. ''CYP2D6'' is primarily expressed in the liver. It is also highly expressed in areas of the central nervous system, including the substantia nigra. CYP2 ...
as well as of several other CYP450 enzymes. As such, CYP450
inhibitor Inhibitor or inhibition may refer to: Biology * Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity * Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotransmi ...
s may increase exposure to CYP450-substrate psychedelics such as LSD and thereby potentiate their effects as well as risks. A clinical study found that administration of LSD to people taking
paroxetine Paroxetine ( ), sold under the brand name Paxil among others, is an Antidepressant, antidepressant medication of the selective serotonin reuptake inhibitor (SSRI) class used to treat major depressive disorder, obsessive-compulsive disorder, o ...
, a
selective serotonin reuptake inhibitor Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder, anxiety disorders, and other psychological conditions. SSRIs primarily work by blo ...
(SSRI) and strong CYP2D6 inhibitor, increased LSD exposure by about 1.5-fold. The combination was well-tolerated and did not modify the pleasant subjective effects or physiological effects of LSD, whereas negative effects of LSD, including "bad drug effect",
anxiety Anxiety is an emotion characterised by an unpleasant state of inner wikt:turmoil, turmoil and includes feelings of dread over Anticipation, anticipated events. Anxiety is different from fear in that fear is defined as the emotional response ...
, and
nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...
, were reduced. Similarly to the findings with a strong CYP2D6 inhibitor, a pharmacogenomic clinical study with LSD found that LSD levels were 75% higher in people with non-functional CYP2D6 (
poor metabolizer Pharmacogenomics, often abbreviated "PGx," is the study of the role of the genome in drug response. Its name ('' pharmaco-'' + ''genomics'') reflects its combining of pharmacology and genomics. Pharmacogenomics analyzes how the genetic makeup o ...
s) compared to those with functional CYP2D6.
Serotonin syndrome Serotonin syndrome (SS) is a group of symptoms that may occur with the use of certain Serotonin, serotonergic medications or Recreational drug use, drugs. The symptoms can range from mild to severe, and are potentially fatal. Symptoms in mild c ...
can be caused by combining psychedelics with other serotonergic drugs, including certain
antidepressant Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction. Common side effects of antidepressants include Xerostomia, dry mouth, weight gain, dizziness, headaches, akathi ...
s,
opioid Opioids are a class of Drug, drugs that derive from, or mimic, natural substances found in the Papaver somniferum, opium poppy plant. Opioids work on opioid receptors in the brain and other organs to produce a variety of morphine-like effects, ...
s,
psychostimulant Stimulants (also known as central nervous system stimulants, or psychostimulants, or colloquially as uppers) are a class of drugs that increase alertness. They are used for various purposes, such as enhancing attention, motivation, cognition ...
s (e.g.
MDMA 3,4-Methylenedioxymethamphetamine (MDMA), commonly known as ecstasy (tablet form), and molly (crystal form), is an empathogen–entactogenic drug with stimulant and minor Psychedelic drug, psychedelic properties. In studies, it has been used ...
),
serotonin Serotonin (), also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter with a wide range of functions in both the central nervous system (CNS) and also peripheral tissues. It is involved in mood, cognition, reward, learning, ...
5-HT1 agonists (e.g.
triptan Triptans are a family of tryptamine-based medication, drugs used as abortive medication in the treatment of migraines and cluster headaches. This drug class was first commercially introduced in the 1990s. While effective at treating individual h ...
s),
herb Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal purposes, or for fragrances. Culinary use typically distingu ...
s or supplements, and others. A high rate of
seizure A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...
s has been reported when people on
lithium Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it is the least dense metal and the ...
have taken serotonergic psychedelics. In an analysis of online reports, 47% of 62accounts reported seizures when a psychedelic was taken while on lithium. The mechanism underlying this apparent interaction is unclear.


Pharmacology


Mechanism of action

Most serotonergic psychedelics act as non-selective
agonist An agonist is a chemical that activates a Receptor (biochemistry), receptor to produce a biological response. Receptors are Cell (biology), cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an R ...
s of
serotonin receptor 5-HT receptors, 5-hydroxytryptamine receptors, or serotonin receptors, are a group of G protein-coupled receptor and ligand-gated ion channels found in multiple tissues including the central and peripheral nervous systems. They mediate both ex ...
s, including of the
serotonin Serotonin (), also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter with a wide range of functions in both the central nervous system (CNS) and also peripheral tissues. It is involved in mood, cognition, reward, learning, ...
5-HT2 receptors, but often also of other serotonin receptors, such as the serotonin 5-HT1 receptors. They are thought to mediate their hallucinogenic effects specifically by activation of serotonin 5-HT2A receptors. Psychedelics (including
tryptamine Tryptamine is an indolamine metabolite of the essential amino acid tryptophan. The chemical structure is defined by an indole—a fused benzene and pyrrole ring, and a 2-aminoethyl group at the second carbon (third aromatic atom, with the firs ...
s like
psilocin Psilocin, also known as 4-hydroxy-''N'',''N''-dimethyltryptamine (4-HO-DMT), is a substituted tryptamine alkaloid and a serotonergic psychedelic. It is present in most psychedelic mushrooms together with its phosphorylated counterpart psilocy ...
, DMT, and
5-MeO-DMT 5-MeO-DMT (5-methoxy-''N'',''N''-dimethyltryptamine), also known as ''O''-methylbufotenin or mebufotenin (), is a naturally occurring psychedelic of the tryptamine family. It is found in a wide variety of plant species, and is also secreted by ...
;
phenethylamine Phenethylamine (PEA) is an organic compound, natural monoamine alkaloid, and trace amine, which acts as a central nervous system stimulant in humans. In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace ami ...
s like
mescaline Mescaline, also known as mescalin or mezcalin, and in chemical terms 3,4,5-trimethoxyphenethylamine, is a natural product, naturally occurring psychedelic drug, psychedelic alkaloid, protoalkaloid of the substituted phenethylamine class, found ...
, DOM, and 2C-B; and
ergoline Ergoline is a core structure in many alkaloids and their synthetic derivatives. Ergoline alkaloids were first characterized in ergot. Some of these are implicated in the condition of ergotism, which can take a convulsive form or a gangrenous for ...
s and lysergamides like
LSD Lysergic acid diethylamide, commonly known as LSD (from German ; often referred to as acid or lucy), is a semisynthetic, hallucinogenic compound derived from ergot, known for its powerful psychological effects and serotonergic activity. I ...
) all act as agonists of the serotonin 5-HT2A receptors. Some psychedelics, such as phenethylamines like DOM and 2C-B, show high selectivity for the serotonin 5-HT2 receptors over other serotonin receptors. There is a very strong correlation between 5-HT2A receptor
affinity Affinity may refer to: Commerce, finance and law * Affinity (law), kinship by marriage * Affinity analysis, a market research and business management technique * Affinity Credit Union, a Saskatchewan-based credit union * Affinity Equity Pa ...
and human hallucinogenic potency. In addition, the intensity of hallucinogenic effects in humans is directly correlated with the level of serotonin 5-HT2A receptor
occupancy {{Short pages monitor