Hallucinogens are a class of drugs that can cause changes in perception, mood, and thought. MESCALINE is a hallucinogenic drug derived from the peyote cactus, which has been used for centuries by indigenous peoples in North America for spiritual and ceremonial purposes. LSD, or lysergic acid diethylamide, is a synthetic hallucinogen that was first synthesized in 1938 and became popular in the 1960s. Both MESCALINE and LSD are powerful hallucinogens that can cause intense visual and auditory hallucinations.