Hallucinogen While many drugs speed up or depress the central nervous system, there is a class of drugs that distorts how we feel, hear, see, smell, taste, and think. Called hallucinogens because users often hallucinate, or experience nonexistent sensations, these drugs are also known as psychedelic, or mind-bending, drugs. Some hallucinogens come from natural sources; others are made in laboratories. Examples of natural hallucinogens are mescaline, psilocybin, DMT, and marijuana. Mescaline, which has been used by American Indians in religious ceremonies, comes from the peyote cactus. Psilocybin, also used by the Indians and believed t