Psilocybin

Psilocybin is the main psychoactive compound in "magic mushrooms," a group of fungi used for their psychedelic effects and, historically, in spiritual and ceremonial settings. In the body it converts to psilocin, which produces effects broadly similar to LSD but typically shorter — generally beginning within 20 to 60 minutes and lasting around four to six hours. Mushrooms are eaten dried or fresh, brewed as tea, or taken as capsules. Psilocybin is generally considered to have low potential for addiction, and fatal poisoning from the compound itself is rare, but the experience can be intensely psychological and unpredictable. It is also the focus of significant medical research — the FDA granted it "breakthrough therapy" designation for depression — though that work occurs in controlled clinical trials, not the unregulated market.

Like LSD, psilocybin (through its active form psilocin) acts mainly on the brain's serotonin system, binding to 5-HT2A receptors in regions governing perception, mood, and cognition. Activating these receptors changes how the brain processes and integrates information, producing altered perception, emotion, and sense of self. Tolerance builds quickly, so repeating doses close together produces diminishing effects, and there is cross-tolerance with LSD. Psilocybin does not produce the compulsive, withdrawal-driven pattern of physically addictive drugs.

A psilocybin experience depends heavily on dose, mindset, and surroundings. Common effects include visual changes (intensified colors, patterns, or movement), an altered sense of time, shifting emotions, introspection, and sometimes a sense of connection or "mystical" experience. Physical effects can include nausea (especially early on), dilated pupils, changes in heart rate and blood pressure, dizziness, and incoordination. As with other psychedelics, the experience can turn frightening — anxiety, panic, paranoia, or confusion — particularly at higher doses or in an unsupportive setting, and impaired judgment can lead to accidents.

Psilocybin's risks are mainly psychological. A difficult experience can involve intense fear, panic, or paranoia, and impaired judgment can lead to unsafe behavior or accidents. People with a personal or family history of psychosis or serious mental illness face a higher risk of a lasting adverse reaction, and rare long-term perceptual disturbances (similar to HPPD) have been described. A distinct and serious danger is misidentification: foraged wild mushrooms are easily confused with poisonous species, and eating the wrong one can cause severe organ damage or death — symptoms of mushroom poisoning (severe vomiting, stomach pain, diarrhea) are a medical emergency. As with all illicit products, what is sold may be mislabeled or adulterated. There is no medication that reverses psilocybin; a hard experience is managed with calm reassurance and a safe setting, and severe agitation, injury, or signs of poisoning warrant emergency care. For poisoning guidance call Poison Control at 1-800-222-1222; for substance-use or mental-health support the SAMHSA National Helpline is 1-800-662-4357.

hallucinations, inability to discern fantasy from reality; panic reaction / psychotic-like episode at high dose

nausea, vomiting, muscle weakness, lack of coordination

longer/more intense trips, psychosis, possible death at overdose; poisoning risk from misidentified toxic mushrooms

none approved federally; under research; some US states authorize supervised use (e.g., Oregon)

isolated from Psilocybe by Albert Hofmann 1957, synthesized 1958; psychiatric research/therapy 1960s; US scheduled 1970