Effects of Psilocybin
"The active compounds in psilocybin-containing 'magic' mushrooms have LSD-like properties and produce alterations of autonomic function, motor reflexes, behavior, and perception.3 The psychological consequences of psilocybin use include hallucinations, an altered perception of time, and an inability to discern fantasy from reality. Panic reactions and psychosis also may occur, particularly if a user ingests a large dose. Long-term effects such as flashbacks, risk of psychiatric illness, impaired memory, and tolerance have been described in case reports."
NIDA InfoFacts, "Hallucinogens: LSD, Peyote, Psilocybin, and PCP" National Institute on Drug Abuse (Bethesda, MD: National Institutes of Health, June 2009)