• Hallucinogens are illegal drugs that alter a person’s perception of reality.
  • These drugs are either synthetically manufactured or derived from plants.
  • Some people may experience ‘flashbacks’, which can occur days, weeks, months or even years after taking the hallucinogen.
Hallucinogens are a type of drug that changes a person’s perception of reality. Also known as ‘psychedelic drugs’, hallucinogens make a person see, feel and hear things that aren’t real, or distort their interpretation of what’s going on around them. Some are quick acting, others take longer to take effect. Being under the influence of a hallucinogen is commonly called ‘tripping’.

Some hallucinogens are manufactured, like LSD (lysergic acid diethylamide), PCP (phencyclidine, or ‘angel dust’) and ketamine. Others are naturally occurring compounds found in particular plants. For instance, the peyote cactus produces the hallucinogen mescaline, while psilocybin is found in certain mushrooms, known as ‘magic mushrooms’.

Types of hallucinogens

Hallucinogens come in a number of different forms. For example:
  • LSD is a powerful drug – typically, small squares of blotting paper or gelatine are soaked in LSD, which are then swallowed, although it may also come in tablets or capsules.
  • PCP usually comes in the form of tablets, capsules or powders of various colours. It is usually swallowed, sniffed or injected, but is sometimes smoked.
  • Ketamine can be made into tablets or pills, or dissolved in liquid. It is usually swallowed, snorted or injected.
  • Magic mushrooms can be cooked, boiled into a drink or eaten raw.
  • Mescaline from the peyote cactus can be found as a white powder, while dried, ground peyote buttons can be found as capsules. It is usually swallowed, but can be chewed or smoked.
Some depressant and stimulant drugs also have a hallucinogenic effect in high doses, including cannabis and ecstasy. Since a person’s sense of distance, time and objective reality are warped when under the influence of hallucinogens, serious injury and accidental death are real risks.

Synthetic hallucinogens

In recent years, a wide range of synthetic products, claiming to have similar effects to hallucinogens, have also been available in Australia. The active ingredient in these products can potentially be a number of chemicals, such as 2C-B or NBOMe, but it is difficult to know what exactly they contain. As a result, they can have more unpredictable effects and are potentially more harmful than hallucinogens.

How hallucinogens work

Hallucinogens target specific centres of the brain to alter its understanding of sensory input. For instance, a person may be looking at a blank wall, but their hallucinating brain may interpret the blank wall as moving and swirling, or perhaps covered in insects.

Effects of hallucinogens

The effects of hallucinogens depend on the type of drug, the strength of the dose, the functioning of the person taking them and their state of mind.

Generally, some of the common effects of hallucinogens include:
  • hallucinations of sight, sound, taste and touch
  • a blurring of the senses, such as sounds being ‘felt’ or colours being ‘heard’
  • feeling detached from the body
  • distortions of time, direction and distance
  • relaxation
  • accelerated heart rate
  • dilated pupils
  • nausea and loss of appetite.

Hallucinogens and ‘bad trips’

Hallucinogens are unpredictable drugs. Just because someone has an enjoyable ‘trip’ the first time, doesn’t guarantee they will always have pleasant experiences.

Every person runs the risk of having a ‘bad trip’. Symptoms can include nightmarish hallucinations, extreme panic, paranoia and nausea. It is also possible to have a mixture of good and bad experiences in the one trip.

Other unpleasant side effects can include:
  • muscle spasms and loss of coordination
  • convulsions and unconsciousness
  • aggressive, hostile and violent behaviour
  • catatonic syndrome, which means the user falls into a ‘zombie-like’ state.
If an overdose is suspected, dial triple zero (000) for an ambulance immediately.

Dependence, tolerance and withdrawal

Like many other drugs, it is possible to build up a tolerance to hallucinogens. This means larger and larger doses need to be taken to achieve the same effect.

Some people develop a psychological dependence and feel that regular drug use is an important part of their lives. Research indicates that people can become physically dependent on hallucinogens like PCP or ketamine. If a person stops taking the drug, they may experience withdrawal symptoms.

Damage from long-term use of hallucinogens

Some people may experience ‘flashbacks’, which can happen days, weeks, months or even years after taking the drug. They briefly relive the hallucinations of a previous trip so powerfully that it seems as if they have been transported back in time and space, or they may experience distortions of their present reality.

Having hallucinations when not under the influence of any hallucinogenic drugs can be very frightening.

Treatment for drug dependence

Treatment options for drug dependence include detoxification, individual counselling and group therapy. See your doctor for information and referral, or contact an alcohol and other drug service in your area.

Where to get help

  • Your doctor
  • Alcohol and other drug service
  • If an overdose is suspected, call triple zero (000) for an ambulance immediately
  • DrugInfo Tel. 1300 85 85 84
  • Direct Line Tel. 1800 888 236 – for 24-hour confidential drug and alcohol telephone counselling, information and referral
  • Family Drug Help – for information and support for people concerned about a relative or friend using drugs Tel. 1300 660 068

Things to remember

  • Hallucinogens are illegal drugs that alter a person’s perception of reality.
  • These drugs are either synthetically manufactured or derived from plants.
  • Some people may experience ‘flashbacks’, which can occur days, weeks, months or even years after taking the hallucinogen.
  • Hallucinogen facts, DrugInfo, Alcohol and Drug Foundation. More information here.
  • Hallucinogens, 2008, NSW Department of Health. More information here.
  • Hallucinogens, 2007, Family Drug Support, Australia. More information here.
  • Lim, D, 2003, ‘Ketamine associated psychedelic effects and dependence’, Singapore Med Journal, vol. 44, no. 1, pp. 31–34. More information here.
  • Degenhardt L, Bruno R, Topp L, 2010, ‘Is ecstasy a drug of dependence?’, Drug and Alcohol Dependence, vol.107, no.1, pp. 1–10. More information here.
  • Cottler L, Leung KS, Abdallah AB, 2009, ‘Test retest reliability of DSM-IV adopted criteria for MDMA abuse and dependence: a cross-national study’, Addiction vol. 104, no. 10, pp. 1679-1690. More information here.
  • Gillespie NA, Neale, MC, Prescott CA, et al. 2007, ‘Factor and item-response analysis DSM-IV criteria for abuse of and dependence on cannabis, cocaine, hallucinogens, sedatives, stimulants and opioids’, Society for the Study of Addiction, vol. 102, no. 6, pp. 920–930. More information here.

More information


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Types of drugs

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This page has been produced in consultation with and approved by: Alcohol and Drug Foundation

Last updated: August 2015

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