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Dementia can cause people to sense or believe things that aren’t real. Although they’re not real, they can feel real and sometimes very scary to the person experiencing them.


Hallucinations are things that you see, hear or otherwise sense that aren’t real.

People living with dementia might have hallucinations that seem very real and last for some time. Some hallucinations are mild, but they can also be frightening.

Hallucinations often involve family members, but they can be of other people or animals, including spiders and snakes.

Hallucinations are not imaginary or pretend. To the person experiencing them, they seem as real as any other object. After the hallucinations go away, the person can usually understand that the things they experienced weren’t real.


Delusions are where you believe something that isn’t true.

Delusions can seem so real that the person who believes them is not able to understand that it’s not true. Delusions can be confusing and frightening.

If they’re also having hallucinations, they might connect to their delusions. For example, if they see and hear a person who isn’t there, that’s a hallucination. If they start believing that person lives in the room upstairs, that’s a delusion.

It’s common to have delusions where the person believes people are doing things to them against their wishes. They might believe someone is stealing their things, or that they’re being given poison instead of medication.

Delusions feel completely true to the person experiencing them. It’s not usually possible to convince a delusional person that their belief isn’t true, even if it’s bizarre or impossible.

A person experiencing delusions might need other people to get them the medical help they need.


Misidentification is when you wrongly identify yourself or other people. 

For example, someone might not recognise a person they know, or think their reflection is someone else. They might mix people up, or believe voices on the TV are coming from people in the room.

Causes of hallucinations and delusions

Dementia can cause the brain to misinterpret the information it receives. This can lead to hallucinations, delusions and misidentification.

Memory loss caused by dementia can also contribute. For example, someone who’s forgotten where they put something might believe another person has taken the item.

Other causes can include:

  • poor eyesight or hearing
  • physical illness, including infection, fever, constipation, anaemia, respiratory disease and dehydration
  • mental health conditions, such as schizophrenia
  • side effects from medication
  • new or changed environments, care-givers or routines
  • being overwhelmed by too many things happening at once.

What you can do

It can be upsetting if someone close to you with dementia experiences hallucinations, delusions or misidentification. But there are things you can do.

Supporting someone experiencing hallucinations or delusions

If your family member or friend is experiencing a hallucination, delusion or misidentification, you can support them by:

  • calmly reassuring and comforting them. If it’s appropriate, you can try hugging them or stroking their arm
  • working out how the hallucination, delusion or misidentification is affecting them. Sometimes it can be ignored if it’s harmless and not upsetting them
  • gently explaining what is happening. Avoid arguing over delusions: this doesn’t work.
  • responding to the feelings behind the words. For example, they might be frightened or worried
  • making sure they’re wearing their glasses or hearing aid if they use them.
  • distracting them with music, exercise, activities, talking to friends or looking at photos.

Reducing hallucinations or delusions

You can also make changes to help to prevent or reduce hallucinations or delusions. These include:

  • booking in a check-up with their doctor. The doctor can identify triggers, including physical or mental health conditions, or side effects from medication
  • keeping track of any changes in behaviour. This can help you work out patterns or triggers
  • keeping their environment, routine and care-givers as familiar as possible. If they do need to move, bring familiar items with them
  • making sure rooms are well lit, so they can see what’s around them. Try using night lights too
  • keeping spare sets of items that they frequently lose, like glasses or keys.

It’s okay to take care of your own health and happiness. If you're struggling as someone who cares for a person with dementia, contact the free, confidential National Dementia Helpline on 1800 100 500, any time of the day or night, for information, advice and support.

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Last updated
15 December 2023