| Routes of|
|Elimination half-life||1-3 hours |
|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||204.273 g·mol−1|
|3D model (JSmol)|
|Melting point||173 to 176 °C (343 to 349 °F)|
|(what is this?) (verify)|
Psilocin (also known as 4-HO-DMT, 4-hydroxy DMT, psilocine, psilocyn, or psilotsin) is a substituted tryptamine alkaloid and a serotonergic psychedelic substance. It is present in most psychedelic mushrooms  together with its phosphorylated counterpart psilocybin. Psilocin is a Schedule I drug under the Convention on Psychotropic Substances.  Acting on the 5-HT2A receptors, psilocin modulates the production and reuptake of serotonin.  The mind-altering effects of psilocin are highly variable and subjective and resemble those of LSD and DMT.
Psilocin and its phosphorylated cousin, psilocybin, were first isolated and named in 1958 by Swiss chemist Albert Hofmann. Hofmann obtained the chemicals from laboratory-grown specimens of the entheogenic mushroom Psilocybe mexicana . Hofmann also succeeded in finding synthetic routes to these chemicals. 
Psilocin can be obtained by dephosphorylation of natural psilocybin under strongly acidic or under alkaline conditions (hydrolysis). Another synthetic route uses the Speeter–Anthony tryptamine synthesis procedure. 4-hydroxyindole is acylated with oxalyl chloride. The compound is further reacted with an amine, yielding indole-3-yl-glyoxalyamide. Finally, the product amide is reduced using lithium aluminum hydride yielding psilocin. 
Psilocin is relatively unstable in solution due to its phenolic hydroxy (-OH) group. In the presence of oxygen, it readily forms bluish and dark black degradation products.  Similar products are also formed under acidic conditions in the presence of oxygen and Fe3+ ions (Keller's reagent).
Sulfur analogs are known with a benzothienyl replacement  as well as 4-SH-DMT.  1-Methylpsilocin is a functionally 5-HT2C receptor preferring agonist.  4-Fluoro-N,N-dimethyltryptamine is known.  O-Acetylpsilocin (4-AcO-DMT) is an acetylated analog of psilocin. Additionally, replacement of a methyl group at the dimethylated nitrogen with an isopropyl or ethyl group yields 4-HO-MIPT (4-hydroxy-N-methyl-N-isopropyltryptamine) and 4-HO-MET (4-hydroxy-N-methyl-N-ethyltryptamine), respectively. 4-Acetoxy-MET (4-Acetoxy-N-methyl-N-ethyltryptamine), also known as 4-AcO-MET, is the acetate ester of 4-HO-MET, and a homologue of 4-AcO-DMT.
Psilocin is the pharmacologically active agent in the body after ingestion of psilocybin or some species of psychedelic mushrooms.
Psilocybin is rapidly dephosphorylated in the body to psilocin which acts as a 5-HT2A, 5-HT2C and 5-HT1A agonist or partial agonist. Psilocin exhibits functional selectivity in that it activates phospholipase A2 instead of activating phospholipase C as the endogenous ligand serotonin does. Psilocin is structurally similar to serotonin (5-HT),  differing only by the hydroxyl group being on the 4-position rather than the 5 and the dimethyl groups on the nitrogen. Its effects are thought to come from its agonist activity at 5-HT2A serotonin receptors in the prefrontal cortex.
Psilocin has no significant effect on dopamine receptors (unlike LSD) and only affects the noradrenergic system at very high dosages. 
Psilocin's half-life ranges from 1 to 3 hours. 
This section relies largely or entirely upon a single source .(September 2022)
Its physiological effects are similar to a sympathetic arousal state. Specific effects observed after ingestion can include but are not limited to tachycardia, dilated pupils, restlessness or arousal, euphoria, open and closed eye visuals (common at medium to high doses), synesthesia (e.g. hearing colours and seeing sounds), increased body temperature, headache, sweating and chills, and nausea. Psilocin acts as a 5-HT2A, 5-HT2C, and 5-HT1A receptor agonist or partial agonist. Such receptors are claimed to significantly regulate visuals, decision making, mood, decreased blood pressure, and heart rate. 
There has been no direct lethality associated with psilocin.  [ medical citation needed ] There has been no reported withdrawal syndrome when chronic use of this drug is ceased.  [ medical citation needed ] There is cross tolerance among psilocin, mescaline, LSD,  [ medical citation needed ] and other 5-HT2A, 5-HT2C, and 5-HT1A agonists due to down-regulation of these receptors.
The United Nations Convention on Psychotropic Substances (adopted in 1971) requires its members to prohibit psilocybin, and parties to the treaty are required to restrict the use of the drug to medical and scientific research under strictly controlled conditions.
Psilocin is considered a Schedule 9 prohibited substance in Australia under the Poisons Standard (October 2015).  A Schedule 9 substance is a substance which may be abused or misused, the manufacture, possession, sale or use of which should be prohibited by law except when required for medical or scientific research, or for analytical, teaching or training purposes with approval of Commonwealth and/or State or Territory Health Authorities. 
Psilocin and psilocybin are banned in Russia as narcotic drugs with a criminal penalty for possession of at least 50 mg. 
N,N-Dimethyltryptamine is a substituted tryptamine that occurs in many plants and animals, including humans, and which is both a derivative and a structural analog of tryptamine. DMT is used as a psychedelic drug and prepared by various cultures for ritual purposes as an entheogen.
Psilocybin is a naturally occurring psychedelic prodrug compound produced by more than 200 species of fungi. The most potent are members of genus Psilocybe, such as P. azurescens, P. semilanceata, and P. cyanescens, but psilocybin has also been isolated from about a dozen other genera. Psilocybin is itself biologically inactive but is quickly converted by the body to psilocin, which has mind-altering effects similar, in some aspects, to those of lysergic acid diethylamide (LSD), mescaline, and dimethyltryptamine (DMT). In general, the effects include euphoria, visual and mental hallucinations, changes in perception, distorted sense of time, and perceived spiritual experiences. It can also cause adverse reactions such as nausea and panic attacks.
Psychedelics are a subclass of hallucinogenic drugs whose primary effect is to trigger non-ordinary mental states and/or an apparent expansion of consciousness. Sometimes, they are called classic hallucinogens, serotonergic hallucinogens, or serotonergic psychedelics, and the term psychedelic is sometimes used more broadly to include various types of hallucinogens or those which are atypical or adjacent to psychedelia such as MDMA or cannabis; this article uses the narrower definition of psychedelics. True psychedelics cause specific psychological, visual, and auditory changes, and oftentimes a substantially altered state of consciousness. Psychedelic states are often compared to meditative, psychodynamic or transcendental types of alterations of mind. The "classical" psychedelics, the psychedelics with the largest scientific and cultural influence, are mescaline, LSD, psilocybin, and DMT. LSD in particular has long been considered the paradigmatic psychedelic compound, to which all other psychedelics are often or usually compared.
Psilocybe is a genus of gilled mushrooms, growing worldwide, in the family Hymenogastraceae. Most or nearly all species contain the psychedelic compounds psilocybin and psilocin.
Ergoline is a chemical compound whose structural skeleton is contained in a variety of alkaloids, referred to as ergoline derivatives or ergoline alkaloids. Ergoline alkaloids, one being ergine, were initially characterized in ergot. Some of these are implicated in the condition ergotism, which can take a convulsive form or a gangrenous form. Even so, many ergoline alkaloids have been found to be clinically useful. Annual world production of ergot alkaloids has been estimated at 5,000–8,000 kg of all ergopeptines and 10,000–15,000 kg of lysergic acid, used primarily in the manufacture of semi-synthetic derivatives.
DET, also known under its chemical name N,N-diethyltryptamine and as T-9, is a psychedelic drug closely related to DMT and 4-HO-DET. However, despite its structural similarity to DMT, its activity is induced by an oral dose of around 50–100 mg, without the aid of MAO inhibitors, and the effects last for about 2–4 hours.
4-HO-MiPT is a synthetic substituted aromatic compound and a lesser-known psychedelic tryptamine. It is thought to be a serotonergic psychedelic, similar to magic mushrooms, LSD and mescaline. Its molecular structure and pharmacological effects somewhat resemble those of the tryptamine psilocin, which is the primary psychoactive chemical in magic mushrooms.
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 different compounds, it is one of the largest classes of alkaloids. Many of them possess significant physiological activity and some of them are used in medicine. The amino acid tryptophan is the biochemical precursor of indole alkaloids.
4-Hydroxy-5-methoxydimethyltryptamine, also known as 4-HO-5-MeO-DMT or psilomethoxin, is a novel psychedelic drug. It is the 4-hydroxy counterpart of 5-MeO-DMT, or the 5-methoxy counterpart of psilocin.
O-Acetylpsilocin is a semi-synthetic psychoactive drug that has been suggested by David Nichols to be a potentially useful alternative to psilocybin for pharmacological studies, as they are both believed to be prodrugs of psilocin. However, some users report that O-acetylpsilocin's subjective effects differ from those of psilocybin and psilocin. Additionally, some users prefer 4-AcO-DMT to natural psilocybin mushrooms due to feeling fewer adverse side effects such as nausea and heavy body load, which are more frequently reported in experiences involving natural mushrooms. It is the acetylated form of the psilocybin mushroom alkaloid psilocin and is a lower homolog of 4-AcO-MET, 4-AcO-DET, 4-AcO-MiPT and 4-AcO-DiPT.
Ethocybin is a homologue of the mushroom alkaloid psilocybin, and a semi-synthetic psychedelic alkaloid of the tryptamine family. Effects of ethocybin are comparable to those of a shorter LSD or psilocybin trip, although intensity and duration vary depending on dosage, individual physiology, and set and setting.
A serotonin receptor agonist is an agonist of one or more serotonin receptors. They activate serotonin receptors in a manner similar to that of serotonin, a neurotransmitter and hormone and the endogenous ligand of the serotonin receptors.
Aeruginascin or N,N,N-trimethyl-4-phosphoryloxytryptamine is an indoleamine derivative which occurs naturally within the mushrooms Inocybe aeruginascens and Pholiotina cyanopus, and Psilocybe cubensis. Aeruginascin is the N-trimethyl analogue of psilocybin. It is closely related to the frog skin toxin bufotenidine (5-HTQ), a potent 5-HT3 receptor agonist, but the aeruginascin metabolite 4-HO-TMT shows strong binding at the 5-HT2 receptors similar to psilocin. The first scientific literature about the pharmacological effects of aeruginascin is from a study published by Gartz in 1989. Across 23 analyzed cases of accidental hallucinogenic mushroom poisonings, people who had ingested the mushroom Inocybe aeruginascens reported only euphoric experiences. This is in contrast to the slight and in some cases extremely dysphoric experiences reported from the accidental ingestion of non aeruginascin containing mushrooms (containing solely psilocybin and psilocin).
A serotonin releasing agent (SRA) is a type of drug that induces the release of serotonin into the neuronal synaptic cleft. A selective serotonin releasing agent (SSRA) is an SRA with less significant or no efficacy in producing neurotransmitter efflux at other types of monoamine neurons.
4-Hydroxy-α-methyltryptamine (4-HO-αMT) is a psychedelic drug of the tryptamine class. It is a close structural analogue of α-methyltryptamine (αMT) and produces similar effects to it, but with exacerbated side effects similarly to 5-MeO-αMT. Alexander Shulgin describes 4-HO-αMT briefly in his book TiHKAL:
The 4-hydroxy analogue of αMT has been looked at in human subjects. It is reported to be markedly visual in its effects, with some subjects reporting dizziness and a depressed feeling. There were, however, several toxic signs at doses of 15 to 20 milligrams orally, including abdominal pain, tachycardia, increased blood pressure and, with several people, headache and diarrhea.
Substituted tryptamines, or serotonin analogues, are organic compounds which may be thought of as being derived from tryptamine itself. The molecular structures of all tryptamines contain an indole ring, joined to an amino (NH2) group via an ethyl (−CH2–CH2−) sidechain. In substituted tryptamines, the indole ring, sidechain, and/or amino group are modified by substituting another group for one of the hydrogen (H) atoms.
1-Methylpsilocin is a tryptamine derivative which acts as a selective agonist for the 5-HT2C receptor (IC50 of 12 nM, vs 633 nM at 5-HT2A), and an inverse agonist at 5-HT2B (Ki of 38 nM). While 1-methylpsilocin does have higher affinity for 5-HT2C than 5-HT2A, it does produce a head-twitch response in mice that are dependent on 5-HT2A, so it is not entirely free of effects on 5-HT2A in vivo. In contrast to psilocin, 1-methylpsilocin did not activate 5-HT1A receptors in mice. 1-Methylpsilocin has been investigated for applications such as treatment of glaucoma, OCD, and cluster headaches, as these conditions are amenable to treatment with psychedelic drugs but are not generally treated with such agents due to the hallucinogenic side effects they produce, which are considered undesirable. 1-Methylpsilocin therefore represents a potential alternative treatment to psilocin that may be less likely to produce hallucinogenic effects.
5-Chloro-α-methyltryptamine (5-Chloro-αMT), also known as PAL-542, is a tryptamine derivative related to α-methyltryptamine (αMT) and one of only a few known specific serotonin-dopamine releasing agents (SDRAs). It has been investigated in animals as a potential treatment for cocaine dependence. The EC50 values of 5-chloro-αMT in evoking the in vitro release of serotonin (5-HT), dopamine (DA), and norepinephrine (NE) in rat synaptosomes were reported as 16 nM, 54 nM, and 3434 nM, with an NE/DA ratio of 63.6 and a DA/5-HT ratio of 3.38, indicating that it is a highly specific and well-balanced SDRA. However, 5-chloro-αMT has also been found to act as a potent full agonist of the 5-HT2A receptor, with an EC50 value of 6.27 nM and an efficacy of 105%, and almost assuredly acts as a potent agonist of other serotonin receptors as well.
Psilocybin therapy is the use of psilocybin in treating a range of mental health conditions, such as depression, anxiety, addictions, obsessive compulsive disorder, and psychosis. It is one of several forms of psychedelic therapy under study. Psilocybin was popularized as a psychedelic recreational drug in the 1970s and was classified as a Schedule I drug by the DEA. Research on psilocybin as a medical treatment was restricted until the 1990s because of the sociocultural fear of dependence on this drug. As of 2022, psilocybin is the most commonly researched psychedelic due to its safety and low potential for abuse and dependence. Clinical trials are being conducted at universities and there is evidence confirming the use of psilocybin in the treatment of depression, PTSD and end of life anxiety.
4-Propionoxy-N,N-dimethyltryptamine is a synthetic psychedelic drug from the tryptamine family with psychedelic effects, and is believed to act as a prodrug for psilocin. It produces a head-twitch response in mice. It has been sold online as a designer drug since May 2019. It was first identified as a new psychoactive substance in Sweden, in July 2019.