What causes hallucinations?

The specific cause of hallucinations is not known, but they can be associated with some psychiatric disorders or medical conditions. Substance abuse and withdrawal, medication side effects, sensory loss, sleep deprivation, and severe fatigue can all be associated with hallucinations.

Psychiatric causes of hallucinations

Hallucinations may be caused by psychiatric conditions including:

  • Bipolar disorder
  • Psychotic depression (depression with disordered thought processes)
  • Schizoid personality disorder (disorder characterized by detachment and isolation)
  • Schizophrenia
  • Schizotypal personality disorder (disorder characterized by a need for isolation, odd beliefs, and disordered thinking)

Other causes of hallucinations

Hallucinations can have other causes including:

  • Brain tumors
  • Delirium
  • Dementia
  • Medication side effects
  • Seizure disorders
  • Severe fatigue
  • Sleep deprivation
  • Substance abuse
  • Vision or hearing loss

Serious or life-threatening causes of hallucinations

In some cases, hallucinations may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

  • Acute delirium (sudden onset of mental status changes due to illness or toxicity)
  • Seizures
  • Severe infections
  • Stroke

Questions for diagnosing the cause of hallucinations

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your hallucinations including:

  • When did you first experience hallucinations?
  • What types of hallucinations are you having?
  • Can you describe your hallucinations?
  • Did any events or stresses precede your hallucinations?
  • Do you have any other symptoms?
  • Do you have any psychiatric or medical problems?
  • What medications are you taking?
  • Do you drink any alcohol?
  • Are you using any illicit drugs?

What are the potential complications of hallucinations?

Because hallucinations can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Brain damage
  • Coma
  • Difficulties at work, in school, in social environments, and with relationships
  • Drug and alcohol use and abuse
  • Drug overdose or alcohol poisoning
  • Increased risk of injury
  • Legal or financial troubles
  • Self-harm
  • Suicide or violence


  1. Hallucinations. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003258.htm.
  2. Hallucinations. Alzheimer’s Association. http://www.alz.org/living_with_alzheimers_hallucinations.asp.
  3. Patkar AA, Mago R, Masand PS. Psychotic symptoms in patients with medical disorders. Curr Psychiatry Rep 2004; 6:216.

What are hallucinations?

Hallucinations are sensations or perceptions that occur in a wakeful state and seem real, but are created by the brain. Hallucinations may be seen, heard, smelled, felt or tasted. They can be pleasant or threatening and may be related to sensations, imagery, or events of the past, or they may be unrelated to experiences. Common hallucinations include hearing voices; seeing objects, lights or pe... Read more about hallucinationsintroduction


What other symptoms might occur with hallucinations?

Hallucinations may accompany other symptoms that vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the brain may also involve other body systems.

Psychological and cognitive symptoms that may occur along with hallucinations

Hallucinations may accompany other psychological or cognitive symptoms including:

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Aug 23, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Mental Health and Behavior