Chemical substances that can alter a person’s perception of reality and cause hallucinations and other alterations of the senses. Hallucinogenic substances occur naturally in plants, fungi, and animals; and they have been used throughout history in a wide variety of highly advanced and preliterate cultures.
A hallucinogen is a type of drug that induces hallucinations. This group includes specific substances often misused, such as LSD, marijuana, mescaline, and psilocybin. Some prescribed medications, like anticholinergic drugs and levodopa, can also occasionally trigger hallucinations.