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A hallucination is a sensory experience, while you are awake and conscious, without any corresponding cause in the external world which could be shared by others.


A hallucination is a sensory experience, while you are awake and conscious, without any corresponding cause in the external world which could be shared by others. So it would include hearing a voice when nobody is speaking and no-one else could hear it; or seeing a person or object which nobody else near you can see.

There can also be hallucinations of touch (such as feeling things crawling over your skin, when there are none); hallucinations of smell or taste occur, but less commonly, and may be more typical of the aura that warns that an epileptic fit is imminent.

Other names

Seeing or hearing things.

Possible causes

Psychotic illnesses such as schizophrenia, or very severe depression or bipolar disorder, or post-traumatic stress disorder. Sleep deprivation; fever; temporal lobe epilepsy, or the aura preceding an epileptic fit. Some brain tumours. Severe physical illness in which one is delirious, such as liver or kidney failure. Sensory deprivation in which one is, temporarily or permanently, blind or deaf. Intoxication by or withdrawal from various drugs and substances of abuse – such as cocaine, or amphetamine, alcohol (especially in delirium tremens).

Hallucinations may be entirely normal in bereavement, in the form of briefly seeing or hearing the loved person who has recently died – but these are brief, and the person experiencing them recognises that they are not real. Other normal hallucinations include hypnagogic hallucinations which can occur as one is falling asleep, and hypnopompic hallucinations which occur when one is waking up. These are brief, and one rapidly recognises that they don’t represent reality.


Not safe until a cause has been established by a doctor, and is being properly treated. While this is being arranged, do not leave the person alone, speak calmly and soothingly, letting them know what is being done. Don’t get over-anxious or talk behind their back.

When to see a doctor

When you recognise that this is what you are experiencing, or when family or friends tell you that this is what is happening to you. When someone in the family starts to hallucinate, arrange for them to see a doctor as soon as possible, and do not leave them alone.

What to expect at the doctor

A careful history and physical examination, perhaps blood and urine tests to check for a number of possible physical illnesses.


This, of course, depends on the cause of the hallucination. Treatment obviously needs, where possible, to focus on clearing up the cause of these experiences. Anti-psychotic medications may help to remove or at least reduce the disturbance caused by the presence of hallucinations.

The information provided in this article was correct at the time of publishing. At Mediclinic we endeavour to provide our patients and readers with accurate and reliable information, which is why we continually review and update our content. However, due to the dynamic nature of clinical information and medicine, some information may from time to time become outdated prior to revision.

In the interest of our patients, in accordance with SA law and our commitment to expertise, Mediclinic cannot subscribe to the practice of online diagnosis. Please consult a medical professional for specific medical advice. If you have any major concerns, please see your doctor for an assessment. If you have any cause for concern, your GP will be able to direct you to the appropriate specialists.