What Are Hallucinogens?

Man Hallucinating
What Are Hallucinogens?. © Getty Images

Question: What Are Hallucinogens?

Answer: Hallucinogens are a class of drugs that causes profound distortions in a person's perceptions of reality, otherwise known as hallucinations. While under the influence of hallucinogens, users might see images, hear sounds or feel sensations that seem to be real, but in reality do not exist.

Almost all hallucinogens contain nitrogen and are classified as alkaloids.

Many hallucinogens have chemical structures similar to those of natural neurotransmitters (acetylcholine-, serotonin-, or catecholamine-like).

The most commonly abuse hallucinoges are:

  • LSD - (d-lysergic acid diethylamide)
  • Mescaline - found naturally in the peyote cactus
  • Psilocybin - from certain types of mushrooms
  • PCP - (phencyclidine) originally an intravenous anesthetic

Natural and Man-Made

Hallucinogens can be man-made or they can come from plants or mushrooms or extracts from plants and mushrooms. Generally, they are divided into two types: classic hallucinogens (LSD) or dissociative drugs (PCP). Either type of hallucinogen can cause users to have rapid, intense emotional swings.

Scientists are not sure exactly how hallucinogens and dissociative drugs produce their effects on the user. It is believed the drugs temporarily disrupt communication between the neurotransmitter systems throughout the brain and spinal cord, according to National Institute on Drug Abuse research.

The regions of the brain that are affected by hallucinogens control mood, sensory perception, sleep, hunger, body temperature, sexual behavior, and muscle control, the NIDA says.

Back to: Hallucinogens FAQ


National Institute on Drug Abuse. "Hallucinogens and Dissociative Drugs." Research Report Series Updated January 2014

National Institute on Drug Abuse. "Hallucinogens - LSD, Peyote, Psilocybin, and PCP." DrugFacts December 2014

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