hallucinogens

Hallucinogens are psychoactive substances that produce alterations in perception, mood, and cognition. They fall into several broad classes: classical psychedelics such as LSD, psilocybin, and mescaline; dissociatives such as ketamine and PCP; and deliriants such as anticholinergic plants that can cause confusion and vivid hallucinations.

Mechanisms differ by class. Classical psychedelics mainly activate 5-HT2A receptors, altering cortical processing and perception. Dissociatives block NMDA receptors and disrupt the integration of sensory input, producing dissociation from the environment. Deliriants block muscarinic acetylcholine receptors, leading to delirium and confusion.

Effects typically include perceptual changes, altered thought and mood, and sometimes spiritual or mystical experiences. Physical effects may include changes in heart rate, blood pressure, and pupil size. Risks include anxiety, impaired judgment, and, at high doses, dangerous behavior; long-term issues can include persistent perceptual changes and triggering psychiatric symptoms in vulnerable individuals.

In research settings, psilocybin and other psychedelics are studied for treatment-resistant depression, anxiety in terminal illness, and PTSD under controlled conditions. Outside supervision, risks rise and legal penalties may apply. Safety considerations emphasize set and setting, and drug purity.

Legal status varies by country and jurisdiction. Most classical psychedelics are controlled substances, though some places have decriminalization or research exemptions.

Historically, many cultures used hallucinogens in ritual contexts. In the West, LSD emerged in the late 1930s, sparked widespread experimentation in the 1960s, and was subsequently regulated. In recent decades, scientific interest has revived with medical trials.