psilocybin
Meaning of psilocybin: The mushroom compound is a prodrug: what reaches the brain is psilocin, released once the body strips a phosphate group away.
Definition of psilocybin
Psilocybin is a compound produced naturally by certain mushrooms, known informally as magic mushrooms. It belongs to a group called the tryptamine alkaloids and is built on a chemical skeleton close to that of serotonin, a signaling molecule in the brain. The compound itself is largely inactive, and the body converts it into psilocin, which produces the effects.
What does it do in the brain?
An enzyme strips a phosphate group from psilocybin within minutes of swallowing, leaving psilocin, and psilocin is the molecule that crosses into the brain. There it binds several serotonin receptors, and one in particular, the 5-HT2A receptor, which is concentrated in the outer layers of the cortex. Activating it loosens the usual separation between brain regions that ordinarily handle distinct jobs. The reported result is altered perception, a distorted sense of time, strong shifts in mood, and hallucinations, meaning sensations that feel entirely real but arise from no external source. Dose, surroundings and expectation shape the experience heavily, which is unusual among drugs and is the reason research protocols control all three.
Is it the same as other psychedelics?
| Substance | How it relates |
|---|---|
| Psilocin | The active form; psilocybin is converted into it inside the body |
| LSD | A laboratory made compound acting at the same receptor, with a far longer effect |
| Mescaline | Found in peyote and related cacti; same receptor, unrelated chemical family |
| Amanita mushrooms | A different fungus containing muscimol, not psilocybin, despite the shared reputation |
Grouping these together as psychedelics reflects a shared action at one receptor rather than any shared chemistry.
What are the recognized harms?
Nausea and vomiting are common early on. Anxiety, fear and disorientation can dominate a session, and the agitation that follows carries a real risk of injury. Judgment and coordination are impaired throughout. People with a personal or family history of psychotic illness are considered at particular risk, since the effects can set off a lasting episode. Some describe visual disturbances that persist long afterward. A separate hazard has nothing to do with the compound at all: wild mushrooms are easily misidentified, and lookalike species include ones that destroy the liver. Psilocybin is a controlled substance under federal law in the United States and restricted in most other countries, so possession outside an authorized research or specifically permitted setting is unlawful.
Also known as
Used in a sentence
Laboratory testing confirmed the presence of psilocybin in the ingested mushroom sample.
Good to know
Psilocybin's classification as a controlled substance is a distinct issue from its investigational use in supervised clinical research, where it may be administered legally under specific regulatory authorization despite its restricted general legal status.
Word origin
Where “psilocybin” comes from
Shares its name with the mushroom genus Psilocybe, from Greek psilos, meaning bare or smooth, and kybe, meaning head, describing the smooth cap of these mushrooms.