Psychedelic drug


Psychedelics are a subclass of hallucinogenic drugs whose primary effect is to trigger non-ordinary mental states and a perceived "expansion of consciousness". Also referred to as classic hallucinogens or serotonergic hallucinogens, the term psychedelic is sometimes used more broadly to include various other types of hallucinogens as well, such as those which are atypical or adjacent to psychedelia like ketamine and MDMA, respectively.
Classic psychedelics generally cause specific psychological, visual, and auditory changes, and oftentimes a substantially altered state of consciousness. They have had the largest influence on science and culture, and include mescaline, LSD, psilocybin, and DMT. There are a large number of both naturally occurring and synthetic serotonergic psychedelics.
Most psychedelic drugs fall into one of the three families of chemical compounds: tryptamines, phenethylamines, or lysergamides. They produce their psychedelic effects by binding to and activating a receptor in the brain called the serotonin 5-HT2A receptor, and hence are a type of serotonin 5-HT2A receptor agonist. By activating serotonin 5-HT2A receptors, they modulate the activity of key circuits in the brain involved with sensory perception and cognition. However, the exact nature of how psychedelics induce changes in perception and cognition via the serotonin 5-HT2A receptor is still unknown. The psychedelic experience is often compared to non-ordinary forms of consciousness such as those experienced in meditation, mystical experiences, and near-death experiences, which also appear to be partially underpinned by altered default mode network activity. The phenomenon of ego death is often described as a key feature of the psychedelic experience.
Many psychedelic drugs are illegal to possess without lawful authorisation, exemption or license worldwide under the UN conventions, with occasional exceptions for religious use or research contexts. Despite these controls, recreational use of psychedelics is common. There is also a long history of use of naturally occurring psychedelics as entheogens dating back thousands of years. Legal barriers have made the scientific study of psychedelics more difficult. Research has been conducted, however, and studies show that psychedelics are physiologically safe and rarely lead to addiction. Studies conducted using psilocybin in a psychotherapeutic setting reveal that psychedelic drugs may assist with treating depression, anxiety, alcohol addiction, and nicotine addiction. Although further research is needed, existing results suggest that psychedelics could be effective treatments for certain mental health conditions. A 2022 survey by YouGov found that 28% of Americans had used a psychedelic at some point in their life.

Examples

  • LSD is a derivative of lysergic acid, which is obtained from the hydrolysis of ergotamine. Ergotamine is an alkaloid found in the fungus Claviceps purpurea, which primarily infects rye. LSD is both the prototypical psychedelic and the prototypical lysergamide. As a lysergamide, LSD contains both a tryptamine and phenethylamine group within its structure. Uniquely among psychedelics, LSD agonises dopamine receptors as well as serotonin receptors. Drugs like ALD-52, 1P-LSD, and 1V-LSD are prodrugs of LSD.
  • Psilocin is the dephosphorylated active metabolite of the indole alkaloid psilocybin and a substituted tryptamine, which is produced by hundreds of species of psilocybin-containing mushrooms. Of the classical psychedelics, psilocybin has attracted the greatest academic interest regarding its ability to manifest mystical experiences, although all psychedelics are capable of doing so to variable degrees. 4-AcO-DMT is a synthetic acetylated analogue of psilocin and is a prodrug of psilocin similarly to psilocybin.
  • Mescaline is a phenethylamine alkaloid found in various species of cacti, the best-known of these being peyote and the San Pedro cactus. Mescaline has effects comparable to those of LSD and psilocybin. Ceremonial San Pedro use seems to be characterized by relatively strong spiritual experiences, and low incidence of challenging experiences.
  • DMT is an indole alkaloid found in various species of plants. Traditionally, it is consumed by tribes in South America in the form of ayahuasca. A brew is used that consists of DMT-containing plants as well as plants containing monoamine oxidase inhibitors, like harmine and harmaline, which allows DMT to be consumed orally without being rendered inactive by monoamine oxidase enzymes in the digestive system. A pharmaceutical version of ayahuasca is called pharmahuasca. In the Western world, DMT is more commonly consumed via the vaporisation of freebase DMT. Whereas ayahuasca typically lasts for several hours, inhalation has an onset measured in seconds and has effects measured in minutes, being much more intense. Particularly in smoked or vaporised form, DMT has the ability to cause users to enter a hallucinatory realm fully detached from reality, being typically characterised by hyperbolic geometry, and described as defying visual or verbal description. Users have also reported encountering and communicating with entities within this hallucinatory state. DMT is the archetypal substituted tryptamine, being the structural scaffold of psilocybin and, to a lesser extent, the lysergamides.
  • 5-MeO-DMT is a naturally occurring substituted 5-methoxytryptamine which was first identified as having psychedelic effects in the 1960s. It is found in certain hallucinogenic snuffs and in Incilius alvarius toad venom. 5-MeO-DMT is about 5- to 20-fold more potent by weight than DMT. It produces atypical psychedelic effects, including powerful experiences but a relative absence of visual effects, with these experiences often described as "whiteouts". 5-MeO-DMT is usually smoked similarly to DMT and has been described as the "most powerful" known psychedelic or as the "Mount Everest" of psychedelics. The atypical effects of 5-MeO-DMT are thought to be related to strong concomitant activity at the serotonin 5-HT1A receptor.
  • 2C-B is a substituted phenethylamine first synthesized in 1974 by Alexander Shulgin. 2C-B has been described as both a psychedelic and a mild entactogen, with its psychedelic effects increasing and its entactogenic effects decreasing with dose. 2C-B is the most well-known compound in the 2C family, their general structure being discovered as a result of modifying the structure of mescaline. It is also the most widely used synthetic phenethylamine psychedelic.
MDMA is sometimes said to also have weak psychedelic effects, but it acts and is classified mainly as an entactogen rather than as a hallucinogen. Certain related drugs like MDA and MMDA, while much less common, have greater psychedelic effects however.

Uses

Recreational

Recreational use of psychedelics has been common since the psychedelic era of the mid-1960s and continues to feature at festivals and events such as Burning Man. A 2013 survey found that 13.4% of American adults had used a psychedelic at some point in their lives.
A June 2024 report by the RAND Corporation indicated that psilocybin mushrooms are currently the most widely used psychedelic drug among U.S. adults. According to the RAND national survey, 3.1% of adults reported psilocybin use in the past year, while about 12% reported lifetime use. Similar lifetime prevalence was reported for LSD, whereas MDMA showed lower lifetime use at 7.6%. Fewer than 1% of adults reported using any psychedelic in the past month.
A nationwide survey of 11,299 adults in Germany, published in 2025, found that 5.0% of respondents reported lifetime psychedelic use, with 0.7% reporting use within the past six months. Approximately 3% of respondents had used LSD, LSD analogues, psilocybin, or related substances at least once in their lifetime, and 0.5% had done so within the past six months. Lifetime prevalence of medium-to-high dosing was higher than microdosing. Usage patterns varied by sociodemographic characteristics, including sex, age, residence, income, and marital status.

Traditional

A number of frequently mentioned or traditional psychedelics such as ayahuasca, San Pedro, peyote, and Peruvian torch, psilocybin-containing mushrooms and Tabernanthe iboga all have a long and extensive history of spiritual, shamanic and traditional usage by indigenous peoples in various world regions, particularly in Latin America, but also Gabon, Africa in the case of iboga. Different countries and/or regions have come to be associated with traditional or spiritual use of particular psychedelics, such as the ancient and entheogenic use of psilocybe mushrooms by the native Mazatec people of Oaxaca, Mexico or the use of the ayahuasca brew in the Amazon basin, particularly in Peru for spiritual and physical healing as well as for religious festivals. Peyote has also been used for several thousand years in the Rio Grande Valley in North America by native tribes as an entheogen. In the Andean region of South America, the San Pedro cactus has a long history of use, possibly as a traditional medicine. Archaeological studies have found evidence of use going back two thousand years, to Moche culture, Nazca culture, and Chavín culture. Although authorities of the Roman Catholic church attempted to suppress its use after the Spanish conquest, this failed, as shown by the Christian element in the common name "San Pedro cactus" – Saint Peter cactus. The name has its origin in the belief that just as St Peter holds the keys to heaven, the effects of the cactus allow users "to reach heaven while still on earth." In 2022, the Peruvian Ministry of Culture declared the traditional use of San Pedro cactus in northern Peru as cultural heritage.
Although people of Western culture have tended to use psychedelics for either psychotherapeutic or recreational reasons, most indigenous cultures, particularly in South America, have seemingly tended to use psychedelics for more supernatural reasons such as divination. This can often be related to "healing" or health as well but typically in the context of finding out what is wrong with the individual, such as using psychedelic states to "identify" a disease and/or its cause, locate lost objects, and identify a victim or even perpetrator of sorcery. In some cultures and regions, even psychedelics themselves, such as ayahuasca and the psychedelic lichen of eastern Ecuador that supposedly contains both 5-MeO-DMT and psilocybin, have also been used by witches and sorcerers to conduct their malicious magic, similarly to nightshade deliriants like brugmansia and latua.