Psilocybin (pron.: // SIL-ə-SY-bin) is a naturally occurring psychedelic compound produced by more than 200 species of mushrooms, collectively known as psilocybin mushrooms. The most potent are members of the genus Psilocybe, such as P. azurescens, P. semilanceata, and P. cyanescens, but psilocybin has also been isolated from about a dozen other genera. As a prodrug, psilocybin is quickly converted by the body to psilocin, which has mind-altering effects similar to those of LSD and mescaline. The effects generally include euphoria, visual and mental hallucinations, changes in perception, a distorted sense of time, and spiritual experiences, and can include possible adverse reactions such as nausea and panic attacks.
Psilocybin mushrooms, also known as psychedelic mushrooms, are fungi that contain psychoactive indole alkaloids. There are multiple colloquial terms for psilocybin mushrooms, the most common being shrooms and magic mushrooms. Biological genera containing psilocybin mushrooms include Agrocybe, Conocybe, Copelandia, Galerina, Gerronema, Gymnopilus, Hypholoma, Inocybe, Mycena, Panaeolus, Pluteus, and Psilocybe. There are approximately 190 species of psilocybin mushrooms and most of them fall in the genus Psilocybe.
Psilocybin mushrooms have likely been used since prehistoric times and may have been depicted in rock art. Many cultures have used these mushrooms in religious rites. In modern Western society they are used recreationally for their psychedelic effects. Recent studies done at Imperial College London and Johns Hopkins School of Medicine conclude that when used properly, psilocybin acts as an anti-depressant as suggested by fMRI brain scans.