



A 'hallucinogen' and a 'psychedelic' may refer correctly to the same substance. Psychedelics are considered by many to be the 'traditional' or 'classical hallucinogens'. A 'hallucinogen' in this sense broadly refers to any substance which causes changes in perception or hallucinations, while psychedelics also carry a connotation of psychedelic culture.

Psychedelics (classical hallucinogens)[edit]

One "Blotter" sheet of 900 LSD doses.


The classical hallucinogens are considered to be the representative psychedelics and LSD is generally considered the prototypical psychedelic.[1] In order to refer to the LSD-like psychedelics, scientific authors have used the term "classical hallucinogen" in the sense defined by Glennon (1999): "The classical hallucinogens are agents that meet Hollister's original definition, but are also agents that: (a) bind at 5-HT2 serotonin receptors, and (b) are recognized by animals trained to discriminate 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) from vehicle.[2] Otherwise, when the term 'psychedelic' is used to refer only to the LSD-like psychedelics (a.k.a. the classical hallucinogens), authors explicitly point that they intend 'psychedelic' to be understood according to this more restrictive interpretation (e.g. see Nichols, 2004).[3]


While possessing a unique mechanism of action, cannabis or marijuana has historically been regarded alongside the classic psychedelics.[citation needed]

Research chemicals and designer drugs[edit]

A designer drug is a structural or functional analog of a controlled substance that has been designed to mimic the pharmacological effects of the original drug while at the same time avoid being classified as illegal (by specification as a research chemical) and/or avoid detection in standard drug tests.[5] Many designer drugs and research chemicals are hallucinogenic in nature, such as those in the 2C and 25-NB (NBOMe) families.


Dissociatives produce analgesia, amnesia and catalepsy at anesthetic doses.[6] They also produce a sense of detachment from the surrounding environment, hence "the state has been designated as dissociative anesthesia since the patient truly seems disassociated from his environment."[7] Dissociative symptoms include the disruption or compartmentalization of "...the usually integrated functions of consciousness, memory, identity or perception."[8]p. 523 Dissociation of sensory input can cause derealization, the perception of the outside world as being dream-like, vague or unreal. Other dissociative experiences include depersonalization, which includes feeling dissociated from one's personality; feeling unreal; feeling able to observe one's actions but not actively take control; being unable to associate with one's self in the mirror while maintaining rational awareness that the image in the mirror is the same person.[9][10][11] Simeon (2004) offered "...common descriptions of depersonalisation experiences: watching oneself from a distance (similar to watching a movie); candid out-of-body experiences; a sense of just going through the motions; one part of the self acting/participating while the other part is observing;...."[12]

The classical dissociatives achieve their effect through blocking the signals received by the NMDA receptor set (NMDA receptor antagonism) and include ketamine, methoxetamine (MXE), phencyclidine (PCP), dextromethorphan (DXM), and nitrous oxide.[13][14][15] However, dissociation is also remarkably administered by salvinorin A's (the active constituent in Salvia divinorum shown to the left) potent κ-opioid receptor agonism, though sometimes described as an atypical psychedelic.[16]


Many users of dissociatives have been concerned about the possibility of NMDA antagonist neurotoxicity (NAN). This concern is partly due to William E. White, the author of the DXM FAQ, who claimed that dissociatives definitely cause brain damage.[18] The argument was criticized on the basis of lack of evidence[19] and White retracted his claim.[20] White's claims and the ensuing criticism surrounded original research by John Olney.

In 1989, John Olney discovered that neuronal vacuolation and other cytotoxic changes ("lesions") occurred in brains of rats administered NMDA antagonists, including PCP and ketamine.[21] Repeated doses of NMDA antagonists led to cellular tolerance and hence continuous exposure to NMDA antagonists did not lead to cumulative neurotoxic effects. Antihistamines such as diphenhydramine, barbiturates and even diazepam have been found to prevent NAN.[22] LSD and DOB have also been found to prevent NAN.[23]


Datura innoxia in flower.
Attractive but highly toxic berry of Atropa belladonna
Flowers and foliage of Nicotiana tabacum, the cultivated tobacco.
Single fruiting body of Amanita muscaria
Myristica fragrans fruit, halved, showing within the brown seed (nutmeg) enclosed in its red aril (mace).

Deliriants, as their name implies, induce a state of delirium in the user, characterized by extreme confusion and an inability to control one's actions. They are called deliriants because their subjective effects are similar to the experiences of people with delirious fevers. The term was introduced by David F. Duncan and Robert S. Gold to distinguish these drugs from psychedelics and dissociatives, such as LSD and ketamine respectively, due to their primary effect of causing delirium, as opposed to the more lucid states produced by the other hallucinogens.[24][page needed]

Despite the fully legal status of several common deliriant plants, deliriants are largely unpopular as recreational drugs due to the severe, generally unpleasant and often dangerous nature of the hallucinations produced.[25][page needed]

Typical or classical deliriants are those which block the muscarinic acetylcholine receptors (antagonism). These are said to be anticholinergic. Many of these compounds are produced naturally by plant genera belonging to the nightshade family Solanaceae, such as Datura, Brugmansia and Latua in the New World and Atropa, Hyoscyamus and Mandragora in the Old World.[26] [27] These tropane alkaloids are poisonous and can cause death due to tachycardia-induced heart failure and hyperthermia even in small doses. Additionally, over-the-counter antihistamines such as diphenhydramine (brand name Benadryl) and dimenhydrinate (brand name Dramamine) also have an anticholinergic effect.[28]

Uncured tobacco is also a deliriant due to its intoxicatingly high levels of nicotine.[29]

The fly agaric mushroom, Amanita muscaria, is often informally lumped with the nightshade plants as a deliriant, though regarded as a dissociative with some regularity as well. This may be explained by the familiarity of both A. muscaria and Atropa belladonna to European culture, their formal statuses as deadly poisons, and their generally undesirable, unpleasant, and dangerous nature, with the potential for death from physical and behavioral toxicity a possibility even when dosages are carefully considered.

Nutmeg has deliriant and hallucinogenic effects as well due to some of its psychoactive chemicals, such as myristicin, which may be anticholinergic like the tropane alkaloids of the nightshade plants, or as suggested by Alexander Shulgin, partially metabolized into the empathogen-entactogen MMDA.

See also: Deliriant - PsychonautWiki

History of use[edit]




Traditional religious and shamanic use[edit]

Historically, hallucinogens have been commonly used in religious or shamanic rituals. In this context they are referred to as entheogens, and are used to facilitate healing, divination, communication with spirits, and coming-of-age ceremonies.[31] Evidence exists for the use of entheogens in prehistoric times, as well as in numerous ancient cultures, including Ancient Egyptian, Mycenaean, Ancient Greek, Vedic, Maya, Inca and Aztec cultures. The Upper Amazon is home to the strongest extant entheogenic tradition; the Urarina of the Peruvian Amazon, for instance, continue to practice an elaborate system of ayahuasca shamanism, coupled with an animistic belief system.[32]


Concerning lycanthropy (werewolves) and the use of hallucinogenic drugs, Frida G. Surawicz and Richard Banta wrote "In the first case, this was brought on by LSD and strychnine and continued casual marijuana use... Concerning drugs as causative agents, it is interesting to note that opium has been mentioned in a dual capacity, namely as a drug which can cause lycanthropy as well as a drug for its treatment."[34]

Early scientific investigations[edit]


Hallucinogens after World War II[edit]




Starting in the mid-20th century, psychedelic drugs has been the object of extensive attention in the Western world. They have been and are being explored as potential therapeutic agents in treating depression, posttraumatic stress disorder, obsessive–compulsive disorder, alcoholism,[40] drug addiction,[41][42][43] cluster headaches, and other ailments. Early military research focused on their use as incapacitating agents. Intelligence agencies tested these drugs in the hope that they would provide an effective means of interrogation, with little success.



Legal status and attitudes[edit]






Psychedelics and mental illnesses in long-term users[edit]


No clear connection has been made between psychedelic drugs and organic brain damage. However, hallucinogen persisting perception disorder (HPPD) is a diagnosed condition wherein certain visual effects of drugs persist for a long time, sometimes permanently,[citation needed] although science and medicine have yet to determine what causes the condition.

A large epidemiological study in the U.S. found that other than personality disorders and other substance use disorders, lifetime hallucinogen use was not associated with other mental disorders, and that risk of developing a hallucinogen use disorder was very low.[46]

How hallucinogens affect the brain[edit]

LSD, mescaline, psilocybin, and PCP are drugs that cause hallucinations, which can alter a person's perception of reality. LSD, mescaline, and psilocybin cause their effects by initially disrupting the interaction of nerve cells and the neurotransmitter serotonin.[47] It is distributed throughout the brain and spinal cord, where the serotonin system is involved with controlling of the behavioral, perceptual, and regulatory systems. This also includes mood, hunger, body temperature, sexual behavior, muscle control, and sensory perception. Certain hallucinogens, such as PCP, act through a glutamate receptor in the brain which is important for perception of pain, responses to the environment, and learning and memory. Thus far, there have been no properly controlled research studies on the specific effects of these drugs on the human brain, but smaller studies have shown some of the documented effects associated with the use of hallucinogens.[47]

Naming and taxonomy[edit]

Psychedelic nomenclature[edit]



The word psychotomimetic, meaning "mimicking psychosis", reflects the hypothesis of early researchers that the effects of psychedelic drugs are similar to naturally occurring symptoms of schizophrenia, though it has since been discovered that some psychedelics resemble endogenous psychoses better than others. PCP and ketamine are known to better resemble endogenous psychoses because they reproduce both positive and negative symptoms of psychoses, while psilocybin and related hallucinogens typically produce effects resembling only the positive symptoms of schizophrenia.[48] While the serotonergic psychedelics (LSD, psilocybin, mescaline, etc.) do produce subjective effects distinct from NMDA antagonist dissociatives (PCP, ketamine, dextrorphan), there is obvious overlap in the mental processes that these drugs affect and research has discovered that there is overlap in the mechanisms by which both types of psychedelics mimic psychotic symptoms.[49][50][51] One double-blind study examining the differences between DMT and ketamine hypothesized that classically psychedelic drugs most resemble paranoid schizophrenia while dissociative drugs best mimicked catatonic subtypes or otherwise undifferentiated schizophrenia.[52] The researchers expressed the view that "a heterogeneous disorder like schizophrenia is unlikely to be modeled accurately by a single pharmacological agent."






Leo Hollister's five criteria for establishing that a drug is hallucinogenic are as follows:

(1) in proportion to other effects, changes in thought, perception, and mood should predominate; (2) intellectual or memory impairment should be minimal; (3) stupor, narcosis, or excessive stimulation should not be an integral effect; (4) autonomic nervous system side effects should be minimal; and (5) addictive craving should be absent.[53]

Lewin's classes[edit]



Pharmacological classes of hallucinogens[edit]




See also[edit]


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Works cited

Further reading[edit]



External links[edit]

  • PsychonautWiki is a wiki dedicated to documenting psychoactive drugs and their subjective effects, with an emphasis on hallucinogens and novel psychoactives. The site hosts experience reports, tutorials, and a curated collection of articles.