31st January 2024

Hallucinogens

Background

Several thousand compounds have hallucinogenic properties; these substances can also be referred to as ‘psychedelics.’ Some naturally occur in plants and fungi (such as psilocybin), and others are synthetic in nature (such as LSD, PCP and ketamine).

Hallucinogens can act on both dopamine and serotonin receptors, by increasing the concentration of the neurotransmitters available. Some studies have found that these compounds are ‘psychotomimetic,’ meaning that acute intoxication can cause a temporary psychotic presentation, but potentially also predispose to a syndrome in keeping with a true psychotic disorder. It is proposed that hallucinogen-induced psychosis is associated with higher levels of dopamine.

Presentation

The effects of each hallucinogen will depend on the substance itself and quantity ingested. Common side effects of hallucinogens are visual, auditory and tactile sensory disturbances, altered experience of time and altered perception of objects. For some individuals, mood changes can occur, as well as temporary cognitive impairment.

Dependence is rare, and withdrawal has not been described; most morbidity is due to intoxication. The most common mental disorder related to hallucinogen use is hallucinogen-induced psychotic disorder.

Acute intoxication with hallucinogens is primarily a clinical diagnosis.

Differential diagnosis 

The potential visual and/or auditory sensory disturbances that can be caused by hallucinogen use could mimic an independent psychiatric disorder, such as a form of psychosis. Other substances, such as cannabis, could also cause a similar symptom profile, and concurrent use should be explored as part of management.

Management

At present, as for cannabis and stimulant misuse, psychosocial therapy is the mainstay of treatment for the misuse of hallucinogens, as well as supportive care for any distressing symptoms.

References

• Clinical Guidelines on Drug Misuse and Dependence Update 2017 Independent Expert Working Group. Drug misuse and dependence: UK guidelines on clinical management. UK: Department of Health; 2017.
• Fiorentini A, Cantù F, Crisanti C, Cereda G, Oldani L, Brambilla P. Substance-induced psychoses: An updated literature review. Frontiers in Psychiatry. 2021;12.
• Stringer S, Church L, Keynejad R, Hurn J. Psychiatry P.R.N.: Principles, reality, next steps. Oxford: Oxford University Press; 2020.