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Psychedelic drugs are psychoactive drugs whose primary action is to enhance or amplify the thought processes of the brain. The term is derived from Greek ψυχη (psyche, "mind") and δηλειν (delein, "manifest").

Psychedelic drugs are thought to disable filters which block or suppress signals related to mundane functions from reaching the conscious mind. These signals are presumed to originate in several other functions of the brain, including but not limited to the senses, emotions, memories and the unconscious (or subconscious) mind. This effect is sometimes referred to as mind expanding, or consciousness expanding as your conscious mind becomes aware of (or sometimes assaulted by) things normally inaccessible to it. At high levels this can overwhelm the sense of self and can result in a dissociative state.

The best definition of what is considered a classic or true psychedelic is the following -- “a psychedelic drug is one which, without causing physical addiction, craving, major physiological disturbances, delirium, disorientation, or amnesia, more or less reliably produces thought, mood, and perceptual changes otherwise rarely experienced except in dreams, contemplative and religious exaltation, flashes of vivid involuntary memory and acute psychoses”. (Grinspoon and Bakalar [1979] p.9). Over the decades, the term has been contaminated to include far more substances than originally intended. Many pharmacologists define psychedelic drugs as chemicals which have an LSD or mescaline like action on certain serotonin receptors. This essentially means tryptamines and phenethylamines, as no psychedelics from other chemical families have been discovered, with the possible exception of piperazines. Many people have applied the term psychedelic to other drugs including cannabis, dissociative arylcyclohexylamines such as PCP and ketamine, tropane deliriants such as atropine, or novel psychoactives such as Amanita muscaria and Salvia divinorum. More properly, these should be grouped with psychedelics under the category of entheogens, a term which describes the way a drug is used rather than its pharmacological properties.

Psychedelics have a long history of traditional use in native medicine and religion, where they are prized for their perceived ability to promote physical and mental healing. Native American practitioners using peyote have reported success against alcoholism, and Mazatec practitioners routinely use psilocybin mushrooms for healing and divination.

Classic psychedelics include LSD, psilocybin (one active principle of 'magic mushrooms'), mescaline (one active principle of peyote and the San Pedro cactus), LSA (morning glory seeds) and also Ayahuasca (known in Beatnik literature as yajé), a traditional shamanic tea brewed from plants containing dimethyltryptamine and harmine or harmaline. Some newer synthetics such as MDMA (ecstasy), 2C-B (nexus), DOM (STP) and 5-MeO-DIPT (Foxy Methoxy) have also enjoyed some popularity.

For a long time, it was believed psychedelics were non-toxic to the body, as there were no reported deaths with even massive doses of LSD, mescaline or psilocybin. In 2000, a young man died from an overdose of 2C-T-7, followed soon after by a second 2C-T-7 death. Since then, there have been other deaths from 2C-T-21, AMT and 5-MeO-AMT. There is also at least one reported death from peyote, although this death was probably related to the plethora of chemicals present in the plant. LSD and Psilocybin have demonstrated virtually non-existent toxicity in healthy subjects, even at many-milligram doses thousands of times higher than are taken recreationally. Mescaline has demonstrated low-to-nonexistant toxicity at multiple-gram doses, some 10 times what may be taken recreationally. This is not to say that psychedelic drugs cannot harm an ill-prepared user mentally, as they certainly can and have. Newer "designer drug" psychedelics such as MDMA, 2C-T-7, and other phenethylamine analogues are harder to identify and easier to "cut" (nearly all presenting as a white powder with a bitter taste with doses too small to judge without laboratory-precision scales). The toxicologies of these new drugs have not been well-established, but initial research shows that they have a much-increased risk of idiosyncratic reaction and a much lower therapeutic index than classic psychedelics.

Pharmacological classes of psychedelics, and their general subjective effects

Entries marked with a # are "naturally" occurring.

Serotonergic psychedelics (serotonin 5-HT2A receptor agonists)

Many of the tryptamines and phenethylamines cause remarkably similar effects, despite their different chemical structure. However, most users report that the two families have subjectively different qualities in the "feel" of the experience which are difficult to describe. At lower doses, these include sensory distortions such as the warping of surfaces, shape suggestibility, and color variations. Users often report intense colors that they have not previously experienced, and repetitive geometric shapes are common. Higher doses often cause intense and fundamental distortions of sensory perception such as synaesthesia or the experience of additional spatial, temporal, or time dimensions. Some compounds, such as 2C-B, have extremely tight "dose curves," meaning the difference between a non-event and an overwhelming disconnection from reality can be very slight. There can be very real differences, however, such as 5-MeO-DMT which rarely produces the visual effects typical of other psychedelics. Some drugs, such as the ß-carbolines, produce very different effects from the more standard types of psychedelics.

Empathogens and/or entactogens (serotonin releasers)

The primary effects of the empathogens include openness, euphoria, empathy, love, and heightened self-awareness. Its initial adoption by the dance club sub-culture is probably due to the enhancement of the overall social and musical experience.

Cannabinoids (CB-1 cannabinoid receptor agonists)

  • THC #, the primary active constituent of cannabis (marijuana)

Some effects may include: general change in consciousness, mild euphoria, feelings of general well-being, relaxation or stress reduction, increased appreciation of humor, music and other art, joviality, metacognition and introspection, enhanced recollection of episodic memory, increased sensuality, loss of inhibition, increased awareness of sensation, creative or philosophical thinking, disruption of linear memory, paranoia, agitation, and anxiety, potentiation of other psychedelics, increased awareness of patterns and color.

Other (psychedelic activity questioned)

  • Myristicin # and Elemicin #, from nutmeg

Effects reported are similar to that of cannabis, more so of the cannabidiol component rather than THC, but with a much longer duration, slow onset, and undesirable side effects.

  • Cryogenine (Vertine) #, the active constituent of sinicuichi

Although vertine has anticholinergic properties, use of sinicuichi tends to produce psychedelic effects rather than that of a deliriant (this could possibly be dose related). The primary noted effects include auditory distortions, improved memory and relaxation.

See also


  • L. Grinspoon, J. Bakalar (1979), Psychedelic Drugs Reconsidered. ISBN 0964156857
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