Hallucinations

Alternative names:

sensory hallucinations

Definition:

Something sensed (whether heard, seen, smelled, or felt) that is not caused by an outside event.

Considerations:

A hallucination can be a symptom of many different disease states and conditions. Hallucinations result when brain metabolism is altered from its normal level. High fever, which directly affects brain metabolism, frequently produces hallucinations in children and occasionally in adults. Psychosis may result in hallucinations and although the underlying metabolic abnormality is not fully understood, psychosis does respond, at least partially, to chemical intervention with medications.

Marked derangement of body metabolism seen during renal failure and liver failure may, on occasion, produce hallucinations. External chemicals such as mind-altering drugs (marijuana, psilocybin, LSD and opium) may cause profound hallucinatory experiences.

Withdrawal from medications that cause slowing of the metabolism or sedation may also result in hallucinatory experiences.

Common causes

• recent death of a loved one (A hallucination of hearing or seeing a close relative or friend who has recently died is not uncommon.)
• post-traumatic stress disorder
• adverse reaction or side effect of a drug
• ingestion of a hallucinogenic substance (LSD, peyote, magic mushrooms, psilocybin, opium)
• adverse reaction to alcohol
• withdrawal from alcohol or other depressant drugs
• psychosis
• delirium
• dementia

Note: There may be other causes of hallucinations. This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of this symptom can include unlikely diseases and medications. Furthermore, the causes may vary based on age and gender of the affected person, as well as on the specific characteristics of the symptom such as quality, time course, aggravating factors, relieving factors, and associated complaints. Use the Symptom Analysis option to explore the possible explanations for hallucinations, occurring alone or in combination with other problems.