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Hallucinogen Use Clinical Presentation

  • Author: Brooke S Parish, MD; Chief Editor: Eduardo Dunayevich, MD  more...
Updated: Nov 23, 2015


Most people who take hallucinogens never seek medical attention. Most who do seek attention do so because of a massive overdose, an acute panic reaction, or an accidental ingestion.

  • A history of recent hallucinogen use can often be obtained from the patient or the patient's friends and family. Use all available resources.
  • Organic causes for altered mental state, acute psychosis, and agitation should be sought aggressively.
  • Consider ingestion of drugs that have the potential to cause hyperthermia if patients are in different stages of undress. These drugs include PCP, mescaline, MDMA, and Jimson weed (not discussed in this article). Users of PCP seem to be fond of swimming, probably as a result of this hyperthermia, and drownings have been reported.
  • Persons who present following LSD ingestions most often do so because of a bad trip, characterized by disturbing visual hallucinations, anxiety, and paranoid delusions. An acute panic reaction is frequently observed. Behavior is usually agitated.
  • Patients who ingest peyote often have pronounced GI effects (nausea and vomiting), diaphoresis, and ataxia before the onset of hallucinations.
  • Users of hallucinogenic amphetamines, such as ecstasy, often give a history of rave attendance. Preoccupation with light is common. Bruxism is also a common finding; many users carry something to put in their mouth (eg, an 18-year-old person with a pacifier). Some experts are concerned over long-term mood disorders and potential suicidal behavior in long-term users.
  • PCP users are more likely to present in the custody of law enforcement officials. They often have a blank stare, may be extremely agitated or violent, and may show no regard for pain. Users can be at risk for both suicidal and homicidal behavior. Use of PCP may occasionally be difficult to distinguish from cocaine toxicity.
  • A history of mushroom ingestion, particularly in novices, should prompt a thorough attempt to identify the ingested mushroom and to differentiate it from more toxic varieties.


A complete set of vital signs should be obtained. Hallucinogen use may manifest with tachycardia, hypertension, and hyperthermia. Hypotension, hypoxia, and marked tachycardia or bradycardia are strong clues that imply serious disease.

Sympathomimetic effects are common and often precede the hallucinogenic effects. Findings may include mydriasis, tachycardia, sweating, hyperthermia, ataxia, and vomiting. Note pupil responses where appropriate.

Perform a complete mental status examination on all patients.[9] Affect, speech, appearance, presence of auditory/visual hallucinations, delusional thinking, and suicidal/homicidal ideation should be carefully assessed.

Most persons experiencing the effects of a hallucinogen are awake, alert, and oriented. Obtunded patients or those with a focal neurologic examination should prompt an aggressive search for an organic etiology.

Although nystagmus in any direction can occur with PCP use, rotatory nystagmus is a classic sign.

Trauma resulting from drug-induced behavior is common.

Conjunctival injection is commonly observed with marijuana use.

Toad licking may cause profound drooling, seizures, and cyanosis.

Severe hyperthermia may be observed with PCP or MDMA use.

The subjective experience of using a hallucination can vary tremendously, not only person to person, but also between ingestions. This makes violence potential difficult to predict. Nevertheless, PCP is generally considered to have the most potential for violence and suicidal or homicidal behavior.[10]

Contributor Information and Disclosures

Brooke S Parish, MD Associate Professor, Department of Psychiatry, University of New Mexico School of Medicine

Brooke S Parish, MD is a member of the following medical societies: American College of Physicians, American Psychiatric Association

Disclosure: Nothing to disclose.


Scott Cameron, MD Consulting Staff, Department of Emergency Medicine, Regions Hospital

Scott Cameron, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association

Disclosure: Nothing to disclose.

Michael E Richards, MD, MPA Associate Professor and Chair, Department of Emergency Medicine, University of New Mexico School of Medicine

Michael E Richards, MD, MPA is a member of the following medical societies: American College of Emergency Physicians, National Association of EMS Physicians, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Eduardo Dunayevich, MD Executive Director, Clinical Development, Amgen

Eduardo Dunayevich, MD is a member of the following medical societies: Schizophrenia International Research Society

Disclosure: Received salary from Amgen for employment; Received stock from Amgen for employment.


Ronald C Albucher, MD Chief Medical Officer, Westside Community Services; Consulting Staff, California Pacific Medical Center

Ronald C Albucher, MD is a member of the following medical societies: American Psychiatric Association

Disclosure: Nothing to disclose.

  1. Hermle L, Simon M, Ruchsow M, Geppert M. Hallucinogen-persisting perception disorder. Ther Adv Psychopharmacol. 2012 Oct. 2(5):199-205. [Medline]. [Full Text].

  2. Erritzoe D, Frokjaer VG, Holst KK, et al. In Vivo Imaging of Cerebral Serotonin Transporter and Serotonin2A Receptor Binding in 3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") and Hallucinogen Users. Arch Gen Psychiatry. 2011 Jun. 68(6):562-76. [Medline].

  3. de la Torre R, Farre M. Neurotoxicity of MDMA (ecstasy): the limitations of scaling from animals to humans. Trends Pharmacol Sci. 2004 Oct. 25(10):505-8. [Medline].

  4. Wilcox JA, Wilcox AH. Movement disorders and MDMA abuse. J Psychoactive Drugs. 2009 Jun. 41(2):203-4. [Medline].

  5. Kosentka P, Sprague SL, Ryberg M, Gartz J, May AL, Campagna SR, et al. Evolution of the toxins muscarine and psilocybin in a family of mushroom-forming fungi. PLoS One. 2013. 8(5):e64646. [Medline]. [Full Text].

  6. US Department of Health and Human Services. Results from the 2013 National Survey on Drug Use and Health: Summary of National Findings. Substance Abuse and Mental Health Services Administration. Available at 2014;

  7. SAMHSA. 2003 National Survey on Drug Use and Health. Department of Health and Human Services, Substance Abuse and Mental Health Services Administration, Office of Applied Studies. Available at Accessed: October 30, 2009.

  8. Lin DL, Liu HC, Liu RH. Methylenedioxymethamphetamine-related deaths in Taiwan: 2001-2008. J Anal Toxicol. 2009 Sep. 33(7):366-71. [Medline].

  9. Krebs TS, Johansen PØ. Psychedelics and mental health: a population study. PLoS One. 2013 Aug 19. 8(8):e63972. [Medline]. [Full Text].

  10. Wong SS, Zhou B, Goebert D, Hishinuma ES. The risk of adolescent suicide across patterns of drug use: a nationally representative study of high school students in the United States from 1999 to 2009. Soc Psychiatry Psychiatr Epidemiol. 2013 Oct. 48(10):1611-20. [Medline].

  11. Erowid. The Vaults of Erowid: Documenting the Complex Relationship Between Humans and Psychoactives [Web site]. [Full Text].

  12. Greene SL, Kerr F, Braitberg G. Review article: amphetamines and related drugs of abuse. Emerg Med Australas. 2008 Oct. 20(5):391-402. [Medline].

  13. Halpern JH, Sewell RA. Hallucinogenic botanicals of America: a growing need for focused drug education and research. Life Sci. 2005 Dec 22. 78(5):519-26. [Medline].

  14. Ompad DC, Galea S, Fuller CM, et al. Club drug use among minority substance users in New York City. J Psychoactive Drugs. 2004 Sep. 36(3):397-9. [Medline].

  15. Passie T, Halpern JH, Stichtenoth DO, Emrich HM, Hintzen A. The pharmacology of lysergic acid diethylamide: a review. CNS Neurosci Ther. 2008. 14(4):295-314. [Medline].

  16. Prisinzano TE. Psychopharmacology of the hallucinogenic sage Salvia divinorum. Life Sci. 2005 Dec 22. 78(5):527-31. [Medline].

  17. SAMSHA. Ecstasy, Other Club Drugs, & Other Hallucinogens. Available at

  18. Tucker JR, Ferm RP. Lysergic acid diethylamide and other hallucinogens. Goldfrank LR, Flomenbaum NE, Lewin NA, Weisman RS, Howland MA, Hoffman RS, eds. Goldfrank's Toxicological Emergencies. 6th ed. Stamford, Conn: Appleton & Lange; 1998. 1111-9.

  19. Williams LC, Keyes C. Psychoactive drugs. Ford MD, Delaney KA, Ling LJ, Erickson T, eds. Clinical Toxicology. Philadelphia, Pa: WB Saunders; 2001. 640-9.

Hallucinogens. Claviceps purpurea.
Hallucinogens. Morning glory (Ipomoea violacea).
Hallucinogens. Bufo marinus.
Hallucinogens. Psilocybe coprophilia.
Hallucinogens. Amanita muscaria.
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