medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

, a side effect is an effect of the use of a medicinal

drug A drug is any chemical substance other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect. Consumption of drugs can be via insufflation (medicine), inhalation, drug i ...

or other treatment, usually

adverse Adverse or adverse interest, in law, is anything that functions contrary to a party's interest. This word should not be confused with averse. The most common use of the term is "an interest, claim , or right that is against another’s interest ...

but sometimes beneficial, that is unintended. Herbal and

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 ...

s also have side effects. A drug or procedure usually used for a specific effect may be used specifically because of a beneficial side-effect; this is termed "

off-label use Off-label use is the use of pharmaceutical drugs for an unapproved indication or in an unapproved age group, dosage, or route of administration. Both prescription drugs and over-the-counter drugs (OTCs) can be used in off-label ways, although mo ...

" until such use is approved. For instance,

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

s have long been used as an imaging technique; the discovery of their oncolytic capability led to their use in

radiotherapy Radiation therapy or radiotherapy (RT, RTx, or XRT) is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle ...

for ablation of

malignant Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous benign tumor, ''benign'' tumor in that a malig ...

tumour A neoplasm () is a type of abnormal and excessive growth of tissue (biology), tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tiss ...

Frequency of side effects

The

World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...

and other health organisations characterise the probability of experiencing side effects as: * Very common, ≥ ¹⁄₁₀ * Common (frequent), ¹⁄₁₀ to ¹⁄₁₀₀ * Uncommon (infrequent), ¹⁄₁₀₀ to ¹⁄₁₀₀₀ * Rare, ¹⁄₁₀₀₀ to ¹⁄₁₀₀₀₀ * Very rare, < ¹⁄₁₀₀₀₀ The

European Commission The European Commission (EC) is the primary Executive (government), executive arm of the European Union (EU). It operates as a cabinet government, with a number of European Commissioner, members of the Commission (directorial system, informall ...

recommends that the list should contain only effects where there is "at least a reasonable possibility" that they are caused by the drug and the frequency "should represent crude incidence rates (and not differences or relative risks calculated against placebo or other comparator)". The frequency describes how often symptoms appear ''after'' taking the drug, without assuming that they were necessarily ''caused by'' the drug. Both healthcare providers and lay people misinterpret the frequency of side effects as describing the increase in frequency caused by the drug.

Examples of therapeutic side effects

Most drugs and procedures have a multitude of reported adverse side effects; the information leaflets provided with virtually all drugs list possible side effects. Beneficial side effects are less common; some examples, in many cases of side-effects that ultimately gained regulatory approval as intended effects, are: *

Bevacizumab Bevacizumab, sold under the brand name Avastin among others, is a monoclonal antibody medication used to treat a number of types of cancers and a specific eye disease. For cancer, it is given by slow injection into a vein (intravenous) and use ...

(

Avastin Bevacizumab, sold under the brand name Avastin among others, is a monoclonal antibody medication used to treat a number of types of cancers and a specific eye disease. For cancer, it is given by slow injection into a vein (intravenous) and use ...

), used to slow the growth of blood vessels, has been used against dry age-related

macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred vision, blurred or vision loss, no vision in the center of the visual field. Early on there are often no sym ...

, as well as

macular edema Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye (a yellow central area of the retina) and causes it to thicken and swell ( edema). The swelling may distort a person's central vision, because the ma ...

from diseases such as

diabetic retinopathy Diabetic retinopathy (also known as diabetic eye disease) is a medical condition in which damage occurs to the retina due to diabetes. It is a leading cause of blindness in developed countries and one of the lead causes of sight loss in the wor ...

and

central retinal vein occlusion Central retinal vein occlusion, also CRVO, is when the central retinal vein becomes occluded, usually through thrombosis. The central retinal vein is the venous equivalent of the central retinal artery and both may become occluded. Since the cent ...

. *

Buprenorphine Buprenorphine, sold under the brand name Subutex among others, is an opioid used to treat opioid use disorder, acute pain, and chronic pain. It can be used under the tongue (sublingual), in the cheek (buccal), by injection (intravenous a ...

has been shown experimentally (1982–1995) to be effective against severe, refractory depression. *

Bupropion Bupropion, formerly called amfebutamone, and sold under the brand name Wellbutrin among others, is an atypical antidepressant that is indicated in the treatment of major depressive disorder, seasonal affective disorder, and to support smo ...

(Wellbutrin), an

anti-depressant Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction. Common side effects of antidepressants include dry mouth, weight gain, dizziness, headaches, akathisia, sexua ...

, also helps smoking cessation; this indication was later approved, and the name of the drug as sold for smoking cessation is Zyban. Bupropion branded as Zyban may be sold at a higher price than as Wellbutrin, so some physicians prescribe Wellbutrin for smoking cessation. *

Carbamazepine Carbamazepine, sold under the brand name Tegretol among others, is an anticonvulsant medication used in the treatment of epilepsy and neuropathic pain. It is used as an adjunctive treatment in schizophrenia along with other medications and as ...

is an approved treatment for

bipolar disorder Bipolar disorder (BD), previously known as manic depression, is a mental disorder characterized by periods of Depression (mood), depression and periods of abnormally elevated Mood (psychology), mood that each last from days to weeks, and in ...

and

epileptic 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, but it has side effects useful in treating

attention-deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple con ...

(ADHD),

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 ...

phantom limb A phantom limb is the sensation that an amputated or missing limb is still attached. It is a chronic condition that is often resistant to treatment. When the cut ends of sensory fibres are stimulated during thigh movements, the patient feels as ...

syndrome,

paroxysmal extreme pain disorder Paroxysmal extreme pain disorder originally named familial rectal pain syndrome, is a rare disorder whose most notable features are pain in the mandibular, ocular and rectal areas as well as flushing. PEPD often first manifests at the beginning ...

neuromyotonia Neuromyotonia (NMT) is a form of peripheral nerve hyperexcitability that causes spontaneous muscular activity resulting from repetitive motor unit action potentials of peripheral origin. NMT along with Morvan's syndrome are the most severe types ...

, and

post-traumatic stress disorder Post-traumatic stress disorder (PTSD) is a mental disorder that develops from experiencing a Psychological trauma, traumatic event, such as sexual assault, domestic violence, child abuse, warfare and its associated traumas, natural disaster ...

. *

Dexamethasone Dexamethasone is a fluorinated glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive pulmonary disease (COPD), croup, brain swelling, eye pain following eye su ...

and

betamethasone Betamethasone is a corticosteroid, steroid medication. It is used for a number of diseases including rheumatic disorders such as rheumatoid arthritis and systemic lupus erythematosus, skin diseases such as dermatitis and psoriasis, allergic co ...

premature labor Preterm birth, also known as premature birth, is the Childbirth, birth of a baby at fewer than 37 weeks Gestational age (obstetrics), gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 ...

, to enhance pulmonary maturation of the fetus. *

Doxepin Doxepin is a medication belonging to the tricyclic antidepressant (TCA) class of drugs used to treat major depressive disorder, anxiety disorders, chronic hives, and insomnia. For label updates seFDA index page for NDA 022036/ref> For hives it ...

has been used to treat

angioedema Angioedema is an area of swelling (edema) of the lower layer of skin and tissue just under the skin or mucous membranes. The swelling may occur in the face, tongue, larynx, abdomen, or arms and legs. Often it is associated with hives, which are ...

and severe allergic reactions due to its strong

antihistamine Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides ...

properties. *

Gabapentin Gabapentin, sold under the brand name Neurontin among others, is an anticonvulsant medication primarily used to treat neuropathic pain and also for partial seizures of epilepsy. It is a commonly used medication for the treatment of neuropath ...

, approved for treatment of

seizures 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 ...

and

postherpetic neuralgia Postherpetic neuralgia (PHN) is neuropathic pain that occurs due to damage to a peripheral nerve caused by the reactivation of the varicella zoster virus ( herpes zoster, also known as shingles). PHN is defined as pain in a dermatomal distributi ...

in adults, has side effects which are useful in treating bipolar disorder,

essential tremor Essential tremor (ET), also called benign tremor, familial tremor, and idiopathic tremor, is a medical condition characterized by involuntary rhythmic contractions and relaxations ( oscillations or twitching movements) of certain muscle groups i ...

hot flashes Hot flushes are a form of flushing, often caused by the changing hormone levels that are characteristic of menopause. They are typically experienced as a feeling of intense heat with sweating and rapid heartbeat, and may typically last from tw ...

migraine Migraine (, ) is a complex neurological disorder characterized by episodes of moderate-to-severe headache, most often unilateral and generally associated with nausea, and light and sound sensitivity. Other characterizing symptoms may includ ...

prophylaxis,

neuropathic pain Neuropathic pain is pain caused by a lesion or disease of the somatosensory nervous system. Neuropathic pain may be associated with abnormal sensations called dysesthesia or pain from normally non-painful stimuli (allodynia). It may have continuo ...

syndromes, phantom limb syndrome, and

restless leg syndrome Restless legs syndrome (RLS), also known as Willis–Ekbom disease (WED), is a neurological disorder, usually chronic, that causes an overwhelming urge to move one's legs. There is often an unpleasant feeling in the legs that improves temporaril ...

. *

Hydroxyzine Hydroxyzine, sold under the brand names Atarax and Vistaril among others, is an antihistamine medication. It is used in the treatment of itchiness, anxiety, insomnia, and nausea (including that due to motion sickness). It is used either by mou ...

, an antihistamine, is also used as an

anxiolytic 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 ...

. *

Magnesium sulfate Magnesium sulfate or magnesium sulphate is a chemical compound, a salt with the formula , consisting of magnesium cations (20.19% by mass) and sulfate anions . It is a white crystalline solid, soluble in water but not in ethanol. Magnesi ...

in obstetrics for

and

preeclampsia Pre-eclampsia is a multi-system disorder specific to pregnancy, characterized by the new onset of high blood pressure and often a significant amount of protein in the urine or by the new onset of high blood pressure along with significant end- ...

. *

Methotrexate Methotrexate, formerly known as amethopterin, is a chemotherapy agent and immunosuppressive drug, immune-system suppressant. It is used to treat cancer, autoimmune diseases, and ectopic pregnancy, ectopic pregnancies. Types of cancers it is u ...

(MTX), approved for the treatment of

choriocarcinoma Choriocarcinoma is a trophoblastic cancer usually located on the placenta. It is characterized by early hematogenous spread to the lungs. It belongs to the malignant end of the spectrum in gestational trophoblastic disease (GTD). It is also cla ...

, is frequently used for the medical treatment of an unruptured

ectopic pregnancy Ectopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these sympto ...

. * The

SSRI 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 ...

medication

sertraline Sertraline, sold under the brand name Zoloft among others, is an Antidepressant, antidepressant medication of the selective serotonin reuptake inhibitor (SSRI) class used to treat major depressive disorder, generalized anxiety disorder, socia ...

is approved as an antidepressant but delays sexual climax in men, and can be used to treat

premature ejaculation Premature ejaculation (PE) is a male sexual dysfunction that occurs when a male Ejaculation, expels semen (and most likely experiences orgasm) soon after beginning sexual activity, and with minimal penile stimulation. It has also been called ''e ...

. *

Sildenafil Sildenafil, sold under the brand name Viagra among others, is a medication used to treat erectile dysfunction and pulmonary hypertension, pulmonary arterial hypertension. It is also sometimes used off-label for the treatment of certain sym ...

was originally intended for

pulmonary hypertension Pulmonary hypertension (PH or PHTN) is a condition of increased blood pressure in the pulmonary artery, arteries of the lungs. Symptoms include dypsnea, shortness of breath, Syncope (medicine), fainting, tiredness, chest pain, pedal edema, swell ...

; subsequently, it was discovered that it also produces

erection An erection (clinically: penile erection or penile tumescence) is a Physiology, physiological phenomenon in which the penis becomes firm, engorged, and enlarged. Penile erection is the result of a complex interaction of psychological, neural, ...

s, for which it was later approved. *

Terazosin Terazosin, sold under the brand name Hytrin among others, is a medication used to treat symptoms of an enlarged prostate and high blood pressure. For high blood pressure, it is a less preferred option. It is taken by mouth. Common side effec ...

, an α₁-adrenergic antagonist approved to treat benign prostatic hyperplasia (enlarged prostate) and hypertension, is (one of several drugs) used off-label to treat drug induced

diaphoresis Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distributed over much of the ...

and

hyperhidrosis Hyperhidrosis is a medical condition in which a person exhibits excessive perspiration, sweating, more than is required for the Thermoregulation, regulation of body temperature. Although it is primarily a physical burden, hyperhidrosis can deterio ...

(excessive sweating). *

Thalidomide Thalidomide, sold under the brand names Contergan and Thalomid among others, is an oral administered medication used to treat a number of cancers (e.g., multiple myeloma), graft-versus-host disease, and many skin disorders (e.g., complication ...

, a drug sold

over the counter Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid pres ...

from 1957 to 1961 as a

tranquiliser A sedative or tranquilliser is a substance that induces sedation by reducing irritability or excitement. They are central nervous system (CNS) depressants and interact with brain activity, causing its deceleration. Various kinds of sedatives ca ...

and treatment for

morning sickness Morning sickness, also called nausea and vomiting of pregnancy (NVP), is a symptom of pregnancy. Despite the name, nausea or vomiting can occur at any time during the day. Typically the symptoms occur between the 4th and 16th weeks of pregnan ...

of pregnancy, became notorious for causing tens of thousands of babies to be born without limbs and with other conditions, or

stillborn Stillbirth is typically defined as fetal death at or after 20 or 28 weeks of pregnancy, depending on the source. It results in a baby born without signs of life. A stillbirth can often result in the feeling of guilt or grief in the mother. T ...

. The drug, though still subject to other adverse side-effects, is now used to treat

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

s and

skin disorder A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, Nail (anatomy), nails, and related muscle and glands. The major funct ...

s, and is on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...

References

External links

* * {{Authority control Clinical pharmacology

Frequency of side effects

Examples of therapeutic side effects

See also

References

External links