Hallucinations

What are hallucinations?

People having hallucinations sense things that are not real, even though they seem very real to the person having them. Hallucinations may involve any of the senses, such as:

hearing voices when no one is speaking
seeing things that are not there
feeling things crawling on you that are not there
smelling scents that are not there
tasting flavors that are not there.

Smell and taste hallucinations are rare.

Hallucinations are not the same as illusions. Illusions are when you see or hear something and think it is something else. An example is a person who sees a lamp out of the corner of their eye and thinks it is a person. A person having hallucinations may be completely out of touch with reality.

How do they occur?

Some causes of hallucinations include:

fever, especially in children and older adults
serious illness such as liver failure, kidney failure, or brain cancer
mental disorders such as schizophrenia or bipolar disorder
brain damage
dehydration
side effects of medicine
severe lack of sleep
stress
drugs such as LSD, poisonous mushrooms, or PCP
heavy alcohol use or withdrawal.

Some people have hallucinations right before they get a migraine or have a seizure.

What are the symptoms?

There are different kinds of hallucinations:

Visual hallucinations may be unformed shapes or colors, or things such as animals or people. The person sees things that no one else can see. Drugs like LSD may cause visual hallucinations. Blind people sometimes have hallucinations of seeing things. People with dementia also may have this kind of hallucination.
Auditory hallucinations occur when a person hears voices or sounds that no one else hears. People with schizophrenia often have this type of hallucination. Deaf people may have hearing hallucinations. This type also occurs from using cocaine, amphetamine or other similar drugs.
A tactile hallucination is the feeling of something crawling on the skin. These kind of hallucinations most often occur when drugs or alcohol are used.

How are they diagnosed?

Your health care provider will ask about symptoms and examine you. He or she will make sure that a medical problem or mind-altering drugs, such as LSD or cocaine, are not causing the symptoms.

If no medical cause can be found, you may be referred to a mental health professional for further testing.

How are they treated?

Treatment for hallucinations depends on the cause. If hallucinations are rare, or if they do not trouble the person, no treatment may be needed.

Hallucinations caused by mental health disorders, such as schizophrenia can generally be controlled with medicine. If hallucinations are caused by medicine, changing the dose of medicines may correct the problem.

Hallucinations can be scary for the person having them and for anyone around them. When someone is having hallucinations, it is important to keep calm. If someone is having constant or severe hallucinations, call for emergency help.

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIA File BHV3331F.HTM Release 9.0/2006