Hallucinogens are drugs that cause hallucinations-profound distortions in a person’s perceptions of reality. Under the influence of hallucinogens, people see images, hear sounds, and feel sensations that seem real but do not exist. Some hallucinogens also produce rapid, intense emotional swings. Hallucinogens cause their effects by disrupting the interaction of nerve cells and the neurotransmitter serotonin. Distributed throughout the brain and spinal cord, the serotonin system is involved in the control of behavioral, perceptual, and regulatory systems, including mood, hunger, body temperature, sexual behavior, muscle control, and sensory perception. LSD (an abbreviation for “Lysergic Acid Diethylamide”) is the drug most commonly identified with the term “hallucinogen” and the most widely used in this class of drugs.
Dissociative drugs’ properties – Drugs such as PCP (phencyclidine) and ketamine, which were initially developed as general anesthetics for surgery, distort perceptions of sight and sound and produce feelings of detachment – dissociation – from the environment and self. But these mind-altering effects are not hallucinations. PCP and ketamine are therefore more properly known as “dissociative anesthetics.”
LSD effects – The precise mechanism by which LSD alters perceptions is still unclear. LSD’s effects typically begin within 30 to 90 minutes of ingestion and may last as long as 12 hours. Users refer to LSD and other hallucinogenic experiences as “trips” and to the adverse experiences as “bad trips.” Although most LSD trips include both pleasant and unpleasant aspects, the drug’s effects are unpredictable and may vary with the amount ingested and the user’s personality, mood, expectations, and surroundings. Two long-term effects, persistent psychosis and hallucinogen persisting perception disorder (HPPD), more commonly referred to as “flashbacks”, have been associated with use of LSD.