Hallucinations and dementia

Dementia may cause a person to have hallucinations or see things that aren't there. This is most common in people living with dementia with Lewy bodies, although other types of dementia may also cause hallucinations. 

What are hallucinations?

A hallucination is an experience of something that is not really there. It can involve any or all of the senses.

Visual hallucinations (seeing things that aren't there) are the most common type experienced by people with dementia. They can be simple (for example, seeing flashing lights) or complex (for example, seeing animals, people or strange situations).

People with dementia are often thought to be hallucinating when in fact they are simply mistaken about what they have seen (see Misperceptions and misidentifications, and dementia ).

What causes hallucinations?

Visual hallucinations are usually caused by damage to the brain. They are more common in people with dementia with Lewy bodies and Parkinson’s disease dementia. People with Alzheimer’s disease can also have hallucinations.

Hallucinations can also be caused by physical illness including fever, seizure, stroke, migraine and infection. Diseases that cause inflammation and infection, such as pneumonia, can interfere with brain function and cause delirium. Some people with delirium will have hallucinations. Delirium is a medical emergency.

Hallucinations are a rare side effect of many medications. The drugs for Parkinson’s disease can often trigger hallucinations. Speak to your GP before making any changes to medication.

Some people with worsening vision start to see things that aren’t there (visual hallucinations) because of their deteriorating sight and not from any other condition, such as dementia or a mental health problem. This is called Charles Bonnet syndrome.

How does a person experience hallucinations?

Some people with dementia will have hallucinations in different senses – for example:

  • auditory hallucinations – hearing things that aren’t there, like voices or footsteps
  • olfactory hallucinations – smelling things that aren’t there, such as smoke or perfume
  • tactile hallucinations – physically feeling things that aren’t there, such as being kissed or insects crawling over their skin
  • gustatory hallucinations – tasting things that aren’t there, such as a metallic taste in their mouth.

Visual hallucinations are more common in people with dementia with Lewy bodies, and often take the form of complex, vivid and very realistic hallucinations of people or animals. They often last for several minutes and happen often.

Hallucinations can be extremely distressing, and can lead to the person with dementia becoming frightened and in need of support. However, some people find the hallucinations pleasant or comforting. It often depends on what they are hallucinating and how others respond.

How can hallucinations be treated?

Drug treatments are often not that helpful for people with dementia. However hallucinations, particularly in people with dementia with Lewy bodies, may respond to anti-dementia drugs.

Antipsychotic medication can sometimes help to reduce severe or distressing hallucinations. They should only be used when other treatments have not worked, as they can cause unpleasant or dangerous side-effects. This medication should be regularly reviewed.

People with dementia with Lewy bodies are at particular risk of severe harmful reactions to antipsychotic medication. For more information see Non-drug approaches to changes in mood and behaviour.

How can you tell if someone is hallucinating?

Sometimes the person may appear to be hallucinating, but there is another cause (for example, it is a misperception instead). The following tips can help to identify hallucinations:

  • Hallucinations differ from misperceptions or misidentifications. Listen to what the person is describing, and check if anything could be causing what they are experiencing. For example, if they describe a ‘swarm of insects’, and there is a busy pattern on a carpet, it may be a misperception. By changing or covering the carpet, the misperception may stop.
  • If the person seems to be having auditory hallucinations (hearing things that aren’t there), arrange to have their hearing checked. If the person wears a hearing aid, check that it is working properly at the right setting, and encourage them to wear it. The person may be having problems with their hearing, rather than hallucinating.
  • If the person seems to be having gustatory hallucinations (tasting things that aren’t there), make sure they are getting regular dental check-ups to rule out other causes such as tooth decay or denture cream. For more information see Dental care and oral health.

Supporting a person who is experiencing hallucinations

If the person you care for regularly hallucinates, make an appointment for them to see their GP. 

Make sure the person has regular medication reviews with a pharmacist or GP as new medications, or the combination of their medications, can be a cause of hallucinations. See further down this page for a list of information to take when you visit the GP.

Our dementia advisers are here for you.

When a person is hallucinating, how you respond has a big impact on their experience and wellbeing. If a person is hallucinating, try the following tips.

  • If the person’s hallucinations involve multiple senses, seek medical help immediately, as this can be a sign of serious illness. You should seek medical attention if:
    • the hallucinations frighten the person
    • the hallucinations last a long time
    • the hallucinations happen often
    • the person seems more confused than usual (which may be a sign of delirium).
  • Calmly explain what is happening. If they cannot retain this information, repeat it when they are more relaxed. If this is still not possible, don’t argue with them – it will not help. Trying to convince someone that they are mistaken can lead to more distress.
  • Stay with the person and try to reassure them. Ask them to describe their hallucination.
  • Hallucinations may be limited to a particular setting. Gently leading someone away from where they are having the hallucinations can help make them disappear.
  • Check that the person is not hungry, thirsty or uncomfortable. Dehydration, constipation or infection can lead to delirium, a cause of hallucinations.
  • It may help to distract the person and see if this stops the hallucinations.

People are less likely to hear voices that are not there when they are talking to someone real. Having company may help. They could try a befriending service. See Useful resources.

Seeing the GP for hallucinations

When seeing the GP for support with hallucinations, it will help to bring details of:

  • what the person saw or sensed
  • what time of day it happened, and after what event (for example a nap, meal, or exercise)
  • where it happened, and how long it lasted
  • how the person responded (for example, if they were distressed) and the words they used to describe what they experienced
  • any medication the person is taking and the dosage (including any over-the-counter medications)
  • key details of the person’s medical history, including any long-term health conditions, previous conditions and mental health issues
  • the person’s use of alcohol or other recreational drugs.
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