A Member of the University of Maryland Medical System   |   In Partnership with the University of Maryland School of Medicine

Share

Email PageEmail Print PagePrint

Home > Medical Reference > Encyclopedia (English)

Toggle: English / Spanish

Hallucinations - Overview

Alternative Names

Sensory hallucinations

Definition of Hallucinations:

Hallucinations involve sensing things while awake that appear to be real, but instead have been created by the mind.

Considerations:

Common hallucinations include:

  • Feeling bodily sensations, such as a crawling feeling on the skin or the movement of internal organs
  • Hearing sounds, such as music, footsteps, windows or doors banging
  • Hearing voices when no one has spoken (the most common type of hallucination). These voices may be critical, complimentary, neutral, or may command someone to do something that may cause harm to themselves or to others.
  • Seeing patterns, lights, beings, or objects that aren't there
  • Smelling a foul or pleasant odor

In some cases, hallucinations may be normal. For example, hearing the voice of, or briefly seeing, a loved one who has recently died can be a part of the grieving process.

Common Causes:

There are many causes of hallucinations, including:

  • Being drunk or high, or coming down from such drugs as marijuana, LSD, cocaine (including crack), PCP, amphetamines, heroin, ketamine, and alcohol
  • Delirium or dementia (visual hallucinations are most common)
  • Epilepsy that involves a part of the brain called the temporal lobe (odor hallucinations are most common)
  • Fever, especially in children and the elderly
  • Narcolepsy
  • Psychiatric disorders, such as schizophrenia and psychotic depression
  • Sensory problem, such as blindness or deafness
  • Severe illness, including liver failure, kidney failure, AIDS, and brain cancer
  • Reviewed last on: 2/22/2010
  • David B. Merrill, MD, Assistant Clinical Professor of Psychiatry, Department of Psychiatry, Columbia University Medical Center, New York, NY. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

References

Freudenriech O, Weiss AP, Goff DC. Psychosis and schizophrenia. In: Stern TA, Rosenbaum JF, Fava M, Biederman J, Rauch SL, eds. Massachusetts General Hospital Comprehensive Clinical Psychiatry. 1st ed. Philadelphia, Pa: Mosby Elsevier; 2008:chap 28.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
adam.com
 
Adam QualityA.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
adam.com
Connect with UMMC
Facebook Twitter YouTube Blog iPhone

Please rate the quality of this article.

Do you find this article to be helpful / informative?
              
Poor                                       Excellent

Do you have any brief comments on this page: (up to 255 characters)

© 2011 University of Maryland Medical Center (UMMC). All rights reserved.
UMMC is a member of the University of Maryland Medical System,
22 S. Greene Street, Baltimore, MD 21201. TDD: 1-800-735-2258 or 1.866.408.6885