Encyclopedia of Psychopharmacology

Living Edition
| Editors: Ian P. Stolerman, Lawrence H. Price

Hallucinogen Abuse and Dependence

  • John H. HalpernEmail author
  • Joji Suzuki
  • Pedro E. Huertas
  • Torsten Passie
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27772-6_43-2


Hallucinogen abuse and dependence are known complications resulting from the illicit use of drugs in this category, such as LSD and psilocybin. Users do not experience withdrawal symptoms, but the general criteria for substance abuse and dependence otherwise apply. Dependence is estimated in approximately 2 % of recent-onset users in the United States. Acute hallucinogen intoxication may induce a plethora of physical and psychological effects that can become so overwhelming to the user as to result in seeking emergency psychiatric care. Providing supportive psychotherapy usually proves effective, though sometimes the use of a sedative hypnotic for anxiety is indicated in addition. No randomized controlled trials have examined treatments of hallucinogen abuse or dependence, but standard treatments (motivational interviewing, relapse prevention, outpatient counseling, participation in self-help groups, family therapy) should still be offered.

Role of Pharmacotherapy

Both hallucinogen abuse and hallucinogen dependence are characterized by patterns of compulsive and repeated drug use despite the knowledge of significant harm caused by the activity. However, it is important to point out that hallucinogen use very rarely leads to the development of classic dependence syndromes, such as those seen with opiates or alcohol. As a class, the hallucinogens lack significant direct effect on the dopamine-mediated reward system, and studies to date have failed to train animals to self-administer these compounds as is typical for dependence-inducing drugs (Nichols 2004). In contrast to the users of other substances of abuse, hallucinogen users do not experience withdrawal symptoms and, therefore, this trait is not a criterion for diagnosing hallucinogen dependence. It should also be noted that, in general, tolerance rapidly increases when hallucinogens are used frequently and exponentially so with daily use.

Overall rates of abuse and dependence are thought to be low when compared with other substances (Wright et al. 2007). In the United States, hallucinogen dependence has been estimated in 2 % of recent-onset users (first use within 24 months of survey) and 5 % of past-onset users (first use 24+ months, last use within 12 months), with a relative risk of dependence apparently greater in users with very early age of onset of hallucinogen use (10–11 years old) (Stone et al. 2007). These figures are likely to be an overestimate, as the survey included the non-hallucinogenic structured amphetamine methylenedioxymethamphetamine (MDMA) (that does have entactogenic properties) and the dissociative anesthetic PCP within their definition of hallucinogen.

Similar to other substances of abuse, hallucinogens may induce specific, related disorders. These include hallucinogen intoxication, hallucinogen-induced psychotic, mood, anxiety, delirium, or not otherwise specified (NOS) disorder, and the very rare hallucinogen-persisting perceptual disorder (HPPD). These disorders arise in the context of substance use and may manifest during intoxication, after the acute effects have subsided, or in the days that follow (APA 2013). The diagnosis of a hallucinogen-induced psychotic, mood, anxiety, or delirium disorder is made only if the symptoms are in excess of what is expected from intoxication (APA 2013).

Symptoms, Diagnosis, and Treatment

Hallucinogen ingestion is the central component of hallucinogen use disorders. It is therefore necessary to first discuss the effects, evaluation, and treatment of patients suffering from acute pathological cases of hallucinogen intoxication.

Physical and Psychological Effects of Acute Hallucinogen Intoxication

The typical syndrome of psychological alterations associated with the ingestion of hallucinogens, commonly referred to as “tripping,” may induce a wide variety of emotional, cognitive, and behavioral effects (Table 1) (Hollister 1984). The visual components are typically not true hallucinations but illusions, such as the perception of geometric patterns or scenic dream-like visions appearing before closed eyes, perception of movement in stationary objects, and synesthesias. Content of visual and most emotional phenomena typically reflect the psychodynamics of the user (Leuner 1962). Colors may appear intensified, and altered human and animal forms may appear in the visual field. Hallucinogens activate affectivity and may cause significant changes in mood, where users may change from euphoria to depression or anxiety or vice versa. In some cases, psychotic-like reactions may also be experienced. In short, the psychological effects of hallucinogens are highly variable and strongly influenced by both the individual’s mind-set (Expectancies and their Influence on Drug Effects) and their physical surroundings and social setting. Toxicity of LSD, psilocybin, and other classical hallucinogens is very low (see Passie et al. 2008). Overdosing is possible with respect to psychological reactions, but no case of lethal overdose is known, and there is no evidence of long-term neurocognitive toxicity (Neurotoxicity; Halpern and Pope 1999).
Table 1

Hallucinogena intoxication may include a cluster of the following

Physical effectsb

Psychological effects

Typical (mild to very mild):



 Intensification and lability of affect with euphoria, anxiety, depression, and/or cathartic expressions

 Cardiac palpitation

 Dream-like state

 Hypertension or hypotension

 Sensory activation with illusion, pseudohallucination, hallucination, and/or synesthesia


 Altered experience of time and space


 Altered body image

 Motor incoordination

 Increased suggestibility




 Acute cognitive alterations with loosening of association, inability for goal-directed thinking, and memory disturbance

 Altered neuroendocrine functioning


Typical (mild to strong):



 Sense of perceiving deeper layers of the world, oneself, and others (“consciousness expansion”)


 Mystical experience


 Sense of profound discovery/healing


 (See Ritual Uses of Psychoactive Drugs)




 Psychosomatic complaint


 Impaired judgment



 Blurred vision







 Odd behavior


 Paranoid ideation

 Suicidal ideation

aIndolealkylamine and phenylalkylamine hallucinogens only

bSome effects are reactionary to psychological content (e.g., increased heart rate and nausea due to anxiety), and complaints can be dependent on factors such as mind-set, setting, dose, and supervision. Intoxicated individuals may also deny physical impairment or claim increased energy, sharpened mental acuity, and improved sensory perception

Diagnosis of Acute Hallucinogen Intoxication

Patients present for treatment most often because they experience a panic or depressive reaction, commonly referred to as a “bad trip.” Such reactions can begin any time after the onset of effects and may include fears of “going insane” (Strassman 1984). There may also be paranoid ideation, feelings of being manipulated, or being in a situation without any escape. The acute syndrome of hallucinogen intoxication should be suspected when a patient (or companion) reports recent ingestion of a hallucinogen and presents with a characteristic constellation of sympathomimetic findings with a clear sensorium (unlike NMDA antagonist dissociative anesthetics like PCP that induce a clouding of consciousness). Since laboratory testing is generally not available in most acute settings, obtaining an accurate history and clinical examination is critical in establishing the diagnosis. Street drugs often contain various adulterants; therefore, the actual identity of the ingested substance may not be known. However, the hallucinogens typically produce similar effects, which should be carefully assessed. Signs and symptoms of hallucinogen intoxication are reviewed in the previous section (see Table 1). Physical examination will also provide important clues that can support the diagnosis of hallucinogen intoxication (in particular, widely dilated pupils that do not rapidly/tightly constrict to accommodate bright light). Hallucinogens have varying duration of action; nevertheless, the acute reaction typically lasts less than 10 h (maximum 12–24 h), and reactions lasting longer will require further investigation to rule out other etiologies.

Treatment of Acute Hallucinogen Intoxication

The “talk down” (more accurately the “talk through”) is usually the primary effective intervention indicated in these situations (Taylor et al. 1970). This consists of keeping the patient in a low-stimulus environment (i.e., a quiet space with dimmed lights and minimal distractions) and providing emotional support. Arranging for a reliable sitter (a nonintoxicated companion) to look after the patient is recommended. The sitter can help in keeping the patient calm and oriented by providing a sympathetic presence. In addition, the sitter can also provide reassurance to the patient that the experience is generally nonhazardous, drug induced, and time limited, which will resolve with full recovery. The patient should not be left alone until the effects of the drug wear off.

If severe agitation does not respond to redirection and concerns for safety of the patient or others remain, benzodiazepines are quite effective in reducing anxiety and panic. Many authorities recommend oral diazepam or lorazepam, although intramuscular and intravenous routes are more immediately effective. Avoid physical restraints if possible and limit the use of antipsychotics since paradoxical effects have been reported (Strassman 1984). While no controlled trials have examined the efficacy of antipsychotic drugs for hallucinogen-induced agitation, rare cases may require such an intervention after benzodiazepines have not proven sufficient. However, great caution must be exercised, since first-generation antipsychotics lower the seizure threshold and may also induce hypotension.

Once the acute symptoms subside, patients are usually able to go home accompanied by a companion (Strassman 1984). It is important to advise patients that subsequent ingestion of hallucinogens may precipitate similar reactions. If symptoms persist for longer than 24 h or there are accompanying severe mood or psychotic symptoms that warrant independent clinical attention, hospitalization may be considered.

Gastric lavage should be avoided as it is not effective in removing substances that were usually ingested several hours prior to hospital presentation. Moreover, gastric lavage will invariably worsen the patient’s mental state.

Diagnosis of Hallucinogen Abuse and Dependence

Multiple drug use is common; the differential must always contain other substance use or substance-induced disorders. Alcohol use disorders frequently occur comorbid to hallucinogen abuse and should therefore also be assessed carefully in this population. Schizophrenia, schizophreniform, bipolar, and schizoaffective disorders must also be ruled out in these patients by assessing the longitudinal course of the symptom constellation and their temporal relation to hallucinogen ingestion.

Treatment of Hallucinogen Abuse and Dependence

There are no randomized controlled trials that have examined the treatment of hallucinogen use disorders. However, general principles that apply to other substances of abuse should be employed in treating these patients. Motivational interviewing, detoxification, relapse prevention, intensive outpatient counseling, involvement with self-help groups, and family therapies are examples of interventions that need to be individualized for each particular patient.

Since polysubstance abuse and dependence is common, treatment should also target other substance abuse and dependence that are thought to be contributing to the disturbances. Furthermore, treatment should be provided with a dual diagnosis approach, and any underlying psychiatric disorder should be treated concurrently. No controlled trials have been conducted to evaluate the efficacy of pharmacotherapies.



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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • John H. Halpern
    • 1
    Email author
  • Joji Suzuki
    • 2
  • Pedro E. Huertas
    • 1
  • Torsten Passie
    • 3
  1. 1.Division of Alcohol and Drug AbuseMcLean Hospital, Harvard Medical School, The Laboratory for Integrative PsychiatryBelmontUSA
  2. 2.Department of PsychiatryBrigham and Women’s Hospital, Addiction Psychiatry Service, Harvard Medical SchoolBostonUSA
  3. 3.Department of Psychiatry, Social Psychiatry and PsychotherapyHannover Medical SchoolHannoverGermany