Selenium disulfide, also known as selenium sulfide, is a chemical compound and medication used to treat seborrheic dermatitis,

dandruff Dandruff is a skin condition that mainly affects the scalp. Symptoms include flaking and sometimes mild itchiness. It can result in social or self-esteem problems. A more severe form of the condition, which includes inflammation of the skin, ...

, and pityriasis versicolor. It is applied to the affected area as a lotion or shampoo. Symptoms frequently return if treatment is stopped. Side effects may include hair discoloration, skin irritation, and risk of

systemic absorption Systemic administration is a route of administration of medication, nutrition or other substance into the circulatory system so that the entire body is affected. Administration can take place via enteral administration (absorption of the drug thr ...

and

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, bacterium, or plant, as well as the effect on a subs ...

, among others. Use is not recommended in children less than 2–5 years old. Use in

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ...

breastfeeding Breastfeeding, or nursing, is the process by which human breast milk is fed to a child. Breast milk may be from the breast, or may be expressed by hand or pumped and fed to the infant. The World Health Organization (WHO) recommends that bre ...

has not been studied. It consists of a mixture of

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemis ...

covalent compound A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atom ...

s having an approximate

empirical formula In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, would simply be SO, as is t ...

s of SeS₂. Selenium disulfide acts as a keratolytic and

antifungal An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cry ...

agent. Selenium disulfide was approved for medical use in the United States at least as early as 1951. It 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 ...

. Selenium disulfide is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active c ...

and

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 prescr ...

Medical uses

Selenium disulfide is sold as an

agent in

shampoo Shampoo () is a hair care product, typically in the form of a viscous liquid, that is used for cleaning hair. Less commonly, shampoo is available in solid bar format. Shampoo is used by applying it to wet hair, massaging the product into th ...

s for the treatment of

and seborrheic dermatitis associated in the scalp with fungi of genus '' Malassezia''.Selenium(IV) sulfide - pharmacy codes search engine

It is also used on the body to treat

tinea versicolor Tinea versicolor (also pityriasis versicolor) is a condition characterized by a skin eruption on the trunk and proximal extremities. The majority of tinea versicolor is caused by the fungus ''Malassezia globosa'', although ''Malassezia furfur'' is ...

(pityriasis versicolor), a type of

fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

skin infection caused by a different species of ''Malassezia''. A 2015

systematic review A systematic review is a scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from published studies on t ...

of topical treatments for seborrheic dermatitis of the scalp identified only a single

randomized controlled trial A randomized controlled trial (or randomized control trial; RCT) is a form of scientific experiment used to control factors not under direct experimental control. Examples of RCTs are clinical trials that compare the effects of drugs, surgical ...

evaluating selenium disulfide for the condition. It was a three-arm trial of 246 people with moderate to severe dandruff and compared treatment with 2%

ketoconazole Ketoconazole, sold under the brand name Nizoral among others, is an antiandrogen and antifungal medication used to treat a number of fungal infections. Applied to the skin it is used for fungal skin infections such as tinea, cutaneous can ...

shampoo (n=97), 2.5% selenium disulfide shampoo (n=100), and placebo (shampoo base with no antiseborrheic agent) (n=49) for 29days. The study found a 73% reduction in dandruff score with ketoconazole, a 67% reduction with selenium disulfide, and a 45% reduction with placebo. Based on the study, the systematic review concluded that selenium disulfide may be effective in the treatment of dandruff but that the available evidence is limited and overall

evidence quality Evidence-based medicine (EBM) is "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients". The aim of EBM is to integrate the experience of the clinician, the values of t ...

is low. It also found that while selenium disulfide has infrequent side effects, it seems to have more side effects than ketoconazole shampoo. Consequently, the review concluded that selenium disulfide should not be considered as a

first-line therapy A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health problem, usually following a medical diagnosis. As a rule, each therapy has indications and contraindications. There are many different ...

but instead should be used as an alternative treatment after other therapies like ketoconazole shampoo have proven not effective. A 2015 review recommended topical antifungal agents, topical corticosteroids, and topical calcineurin inhibitors like

tacrolimus Tacrolimus, sold under the brand name Prograf among others, is an immunosuppressive drug. After allogeneic organ transplant, the risk of organ rejection is moderate. To lower the risk of organ rejection, tacrolimus is given. The drug can als ...

as the main treatments for seborrheic dermatitis based on good-quality evidence, rather than selenium disulfide for which evidence is much more limited. However, the review did suggest use of over-the-counter selenium disulfide shampoos as an inexpensive option for managing mild symptoms of seborrheic dermatitis.

Available forms

Selenium disulfide is available in the form of a

prescription drug A prescription drug (also prescription medication or prescription medicine) is a pharmaceutical drug that legally requires a medical prescription to be dispensed. In contrast, over-the-counter drugs can be obtained without a prescription. The rea ...

as a 2.5% medical

. In the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

, a 1% strength is available

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 prescr ...

, and a 2.5% strength is also available with a prescription. In Canada, the 2.5% strength is available over-the-counter. Selsun Blue is an over-the-counter shampoo for dandruff with 1% selenium disulfide as its active ingredient.

Side effects

Side effect In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...

s of selenium disulfide shampoo for dandruff appear to be infrequent. A randomized controlled trial of 100 people who received selenium disulfide reported side effects of itching or burning sensation of the scalp (3people), eruption near the hairline (1person),

psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complet ...

(1person), lightening or bleaching of hair color (2people), orange staining of the scalp (1person), and a chemical taste while shampooing (1person). Selenium disulfide can cause discoloration of nails and light hair and can alter the color of hair dyes. Several scattered case reports of orange to red–brown scalp discoloration with selenium sulfide shampoo exist. The discoloration resolved shortly following discontinuation of selenium disulfide shampoo and its removal could be facilitated by lightly swabbing with

isopropyl alcohol Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable organic compound with a pungent alcoholic odor. As an isopropyl group linked to a hydroxyl group (chemical formula ) it is the simp ...

. Selenium disulfide may also discolor

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typi ...

lic

jewellery Jewellery ( UK) or jewelry ( U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a we ...

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 occurr ...

s of temporary diffuse

hair loss Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarr ...

with selenium disulfide shampoo exist as well. Excessive environmental or occupational exposure to selenium has also been associated with hair loss and other adverse effects. However, hair loss has not been reported with topical selenium disulfide in several large studies. Selenium disulfide should not be applied to damaged skin as there is a risk of

and associated

. Systemic symptoms may include

tremor A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, f ...

weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...

lethargy Lethargy is a state of tiredness, sleepiness, weariness, fatigue, sluggishness or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to inadequate sleep, overexertion, overwor ...

lower abdominal pain Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues. Common causes of pain in the abdomen include gastroenteritis and irritable bowel syndrome. About 15% of people have a mor ...

, and occasional

vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteri ...

. These symptoms usually resolve within 10days following exposure.

Pharmacology

Pharmacodynamics

Selenium disulfide acts as an

and keratolytic agent to treat seborrheic dermatitis and dandruff.

Pharmacokinetics

The systemic absorption and

orally administered Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are i ...

selenium sulfide has been studied in animals. Topical use of selenium sulfide in the form of a shampoo or lotion in humans does not appear to normally increase circulating or urinary selenium levels. However, application of selenium disulfide to damaged skin can result in systemic absorption and has been associated with cases of toxicity. Selenium disulfide appears to be much less toxic than other selenium

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quanti ...

s, which may be attributed to its low

aqueous solubility An aqueous solution is a Solution (chemistry), solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), ...

and very poor systemic absorption.

Chemistry

Composition

Selenium disulfide has a composition that approximates to SeS₂ and is sometimes called selenium sulfide. However, as used in proprietary formulations, it is not a pure chemical compound but a mixture of eight-membered-ring compounds where the overall Se:S ratio is 1:2. The specific chemicals contain a variable number of S and Se atoms, Se_nS_8−n.Cyclic selenium sulfides R. Steudel, R. Laitinen, Topics in Current Chemistry, (1982), 102, 177-197 Many selenium sulfides are known, as indicated by ⁷⁷Se- NMR spectroscopy.

History

Selenium sulfide was introduced for medical use in the United States in 1951. Selenium monosulfide, along with elemental selenium and sulfur, has been used in medicinal preparations in the past, causing confusion and contradiction as to exactly what form selenium is in any given topical preparation.

Society and culture

Popular culture

In the film ''

Evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

'' selenium was mentioned as an active ingredient of Head & Shoulders. A group of academics, therefore, tried to use this brand of shampoo to stop an alien invasion after discovering that the alien life form was sensitive to selenium.

Research

Selenium disulfide has been suggested to be effective as a treatment for

hyperkeratosis Hyperkeratosis is thickening of the stratum corneum (the outermost layer of the epidermis, or skin), often associated with the presence of an abnormal quantity of keratin,Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) ''Robbins & Cotran Pathologi ...

based on a small

case series A case series (also known as a clinical series) is a type of medical research study that tracks subjects with a known exposure, such as patients who have received a similar treatment, or examines their medical records for exposure and outcome. Case ...

of three treated patients. It has also been reported to be effective in the treatment of

scalp psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete ...

based on clinical observation of over 100treated patients and two case reports of dramatic response. Selenium sulfide is under development for the treatment of

meibomianitis Meibomian gland dysfunction (also known as MGD) is a chronic disease of the meibomian glands, which is commonly characterized by obstruction of the end of the duct that delivers the secretion produced by the glands (called meibum) to the eye surf ...

(meibomian gland dysfunction) and dry eyes in topical and ophthalmic formulations. As of March 2021, it is in

phase 2 Michael Lawrence Marrow (August 2, 1955 – December 12, 2019), known as PHASE 2 and Lonny Wood, was an American aerosol paint artist based in New York City. Mostly active in the 1970s, Phase 2 is generally credited with originating the "bubble ...

/ 3

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human subject research, human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel v ...

s for meibomianitis and phase 2 trials for dry eyes. The developmental code name of selenium sulfide for these uses is AZR-MD-001 and it is being developed by Azura Ophthalmics.

References

External links

* {{Portal bar, Medicine Antifungals Cosmetics chemicals Dichalcogenides Interchalcogens Selenium compounds Sulfides World Health Organization essential medicines Wikipedia medicine articles ready to translate