Halusinogen

Halusinogen, or hallucinogen, is a substance that induces perceptual changes such as vivid visual or auditory experiences and alterations in thought, mood, and sense of time. They are commonly categorized into classical or psychedelic hallucinogens, dissociatives, and deliriants. Most classical hallucinogens, including LSD, psilocybin (magic mushrooms), and mescaline, act primarily as agonists at serotonin 2A receptors, disrupting typical cortical and thalamic processing. Dissociatives such as ketamine, PCP, and dextromethorphan block NMDA receptors, producing detachment from the body and environment. Deliriants like anticholinergic drugs can cause delirium and confusion, with less reliance on typical hallucinatory content.

Effects vary but commonly include alterations in perception, time distortion, changes in mood, pupil dilation, and sometimes profound or spiritual experiences. Onset, intensity, and duration depend on the substance and route of administration. Classic psychedelics often last several hours; DMT is rapid and shorter in duration; dissociatives may persist for a few hours depending on dose and formulation.

Risks include psychological reactions such as anxiety, paranoia, or panic, and in some individuals the emergence of persistent perceptual changes or other psychiatric symptoms. Physical effects can include elevated heart rate and blood pressure, nausea, and impaired coordination, increasing the risk of injury. Use is not advised for people with a personal or family history of psychosis or certain heart conditions, and combining substances can be dangerous.

Research has explored potential therapeutic uses for conditions such as depression, anxiety, PTSD, and substance use disorders when conducted in controlled settings. Legal status varies by country and region; many classic hallucinogens are controlled substances, though some jurisdictions allow restricted medical use or have decriminalized possession for personal use.