hallucinogen

Any substance that acts on the central nervous system to produce changes in perception and mood and often hallucinations. Hallucinogens include LSD, peyote, and mescaline. Their effects are unpredictable and they are illegal in most countries.

In some circumstances hallucinogens may produce panic or even suicidal feelings, which can recur without warning several days or months after taking the drug. In rare cases they produce an irreversible psychotic state mimicking schizophrenia. Spiritual or religious experiences are common, hence the ritual use of hallucinogens in some cultures. They work by chemical interference with the normal action of neurotransmitters in the brain.