Hallucinogenic drug

Hallucinogenic drug, consciousness-altering drug that causes hallucinations or illusions, usually visual, together with personality and behavior changes. LSD (lysergic acid diethylamide), mescaline (peyote), and psilocin and psilocybin (derived from certain mushrooms) are common hallucinogenic drugs. The type of hallucination is not predictable, and may be unpleasant. They have been used for centuries in many cultures in connection with religious rituals. Although they are not physically addictive, a high degree of tolerance to LSD and psilocybin develops rapidly, such that higher and higher doses are required to produce an effect. The long-term biological and psychological consequences are unknown.

See also: Drug; Drug abuse.