Hallucinations and delusions in dementia: causes and how to respond

Hallucinations (seeing, hearing or smelling things that are not there) and delusions (firmly believing something untrue, such as that money has been stolen) are common in dementia, especially dementia with Lewy bodies. They are not always caused by the dementia itself: poor eyesight or hearing, an infection causing delirium, pain or a new medicine are frequent triggers, so the first step is a check-up with the GP, and the second is to respond calmly rather than argue.

In short

• Visual hallucinations are a typical early symptom of dementia with Lewy bodies, and the NHS lists hallucinations among the symptoms that can appear in the later stages of other types of dementia.
• A sudden change over hours or days is a warning sign of delirium, often from an infection. The NHS says sudden confusion needs urgent medical help: call 999 or go to A&E.
• Everyone aged 60 or over gets a free NHS sight test, and people who cannot leave home unaccompanied, including some care home residents, may be able to have it at home.
• NICE guideline NG97 says antipsychotics should only be offered when someone is at risk of harm or in severe distress, at the lowest dose and shortest time, and reviewed at least every 6 weeks.
• In Lewy body or Parkinson’s disease dementia, NICE warns antipsychotics can cause severe sensitivity reactions, so always make sure prescribers know the diagnosis.
• Arguing rarely helps. Acknowledge the feeling, reassure, check the surroundings and gently redirect.

Hallucinations, delusions and misperceptions: what is the difference?

Families often use these words interchangeably, but they need different responses, so it helps to name what you are seeing.

Delusions in dementia frequently grow out of memory loss. If your mother cannot remember where she put her purse, the most logical explanation to her may be that someone took it. Seen that way, the belief is an attempt to make sense of a confusing world, not stubbornness.

Why it happens: common causes to rule out

The type of dementia

In dementia with Lewy bodies, the NHS lists visual hallucinations as a typical symptom, along with alertness that changes over minutes or hours, slow movement, falls and disturbed sleep. The same Lewy body protein deposits are found in Parkinson’s disease, and people with Parkinson’s disease dementia can have similar experiences. In Alzheimer’s disease, hallucinations are less common early on and tend to appear later, while delusions about theft or infidelity can occur at any stage. Our guide to the stages of dementia explains how needs change over time.

Delirium

Delirium is a sudden, usually temporary state of confusion, and NICE lists hallucinations among its indicators. People with dementia are at much higher risk. Common causes include urine and chest infections, dehydration, constipation, pain, a fall and medicine changes. The key sign is speed: if your father was settled last week and is now seeing things, agitated or unusually drowsy, think delirium first. Our guide to delirium and UTIs in older people covers this in detail.

Sight and hearing loss

Poor vision makes misperceptions far more likely. People with significant sight loss, for example from macular degeneration or cataracts, can also develop Charles Bonnet syndrome. The NHS describes this as visual hallucinations caused by sight loss rather than by a mental health problem or dementia, so a person with dementia and failing eyesight may have both. Hearing loss can likewise turn background noise into voices. Ask for a sight test and a hearing check, make sure glasses are clean and the right pair, and check hearing aids work.

Medicines, pain and the environment

Some medicines, including some used for Parkinson’s, bladder problems, sleep and pain, can cause or worsen hallucinations. Ask the GP or pharmacist for a medication review, but never stop a prescribed medicine without advice. Untreated pain, tiredness, low light at dusk, shadows, patterned wallpaper, mirrors and a television left on can all add to confusion.

How to respond in the moment

The aim is to reduce fear, not to win the argument. What the person is experiencing feels completely real to them.

1. Stay calm and check for danger. Is there a real hazard, such as a stranger at the door or a pan on the hob? Rule that out first.
2. Acknowledge the feeling, not the content. “That sounds frightening. I’m here and you’re safe” works better than “There’s nobody there.”
3. Do not argue or play along in detail. Contradiction usually increases distress. Equally, avoid inventing elaborate stories that may add to confusion later. A neutral middle path, such as “I can’t see them, but I can see you’re worried,” is often best.
4. Check the surroundings. Turn on a light, close curtains at dusk, cover or remove a mirror, switch off the television.
5. Redirect gently. Move to another room, offer a drink, put on familiar music or start a simple task together.
6. If the experience is pleasant, let it be. Not every hallucination needs fixing. If your mother is happily chatting to a cat she can see, there may be no reason to intervene.
7. Note what happened. Time of day, what came before, how long it lasted. Patterns help the GP and any carers.

Responding to accusations of theft

Accusations against family or carers are among the most painful delusions. Try not to take them personally. Help look for the missing item, keep spares of things that often go missing (glasses, keys, a purse with a little cash) and learn the usual hiding places. Tell paid carers in advance so they are not caught off guard, and ask the agency to log any accusations. Do take a genuine concern seriously: if something really is missing and the pattern is unusual, our guide to signs of neglect or abuse by a carer explains how to raise it.

When to see the GP, call 111 or call 999

Before the appointment, write down the diagnosis, all medicines (including over-the-counter ones), when the symptoms started and examples. If you hold a health and welfare lasting power of attorney, take a copy; it makes it easier for professionals to involve you.

Medicines: what families should know

NICE guideline NG97 on dementia says antipsychotic medicines should only be offered to people who are at risk of harming themselves or others, or who have agitation, hallucinations or delusions causing them severe distress. They should be used at the lowest effective dose for the shortest possible time, reassessed at least every 6 weeks, and stopped if there is no clear ongoing benefit. Before any of this, NICE expects a structured assessment of possible causes such as pain or delirium, and psychosocial and environmental approaches as the first and continuing line of support.

For dementia with Lewy bodies and Parkinson’s disease dementia, NICE warns that antipsychotics can worsen movement problems and cause severe sensitivity reactions. If your relative has either diagnosis, make sure it is clearly recorded and mentioned in any hospital, out-of-hours or care home setting. You are entitled to ask why a medicine is being prescribed, how it will be reviewed and what the alternatives are. In a care home, ask how often antipsychotic prescriptions are reviewed and how the home uses non-drug approaches first.

Looking after yourself, and when more help is needed

Living with someone who believes you are an impostor, or who wakes at 3am convinced there are people in the garden, is exhausting. Your own wellbeing matters. You are entitled to a free carer’s assessment from the council, which can lead to breaks and practical help. Short respite care can give you time to recover.

Consider more support if hallucinations or delusions are frequent, if the person is frightened most days, if they are trying to leave the house to escape someone, or if you are no longer sleeping. Options include evening or overnight dementia care at home, live-in care, or a move to a specialist home. Our guide to choosing a dementia care home lists questions to ask about how staff handle distress. If agitation or aggression is also part of the picture, see our guide to managing aggression and agitation in dementia.

To estimate what extra support might cost, try the care cost calculator. People with dementia who need supervision often qualify for Attendance Allowance at £76.70 or £114.60 a week, which is not means-tested; the Attendance Allowance checker takes a couple of minutes.

Scotland, Wales and Northern Ireland

The clinical advice is the same across the UK, though NICE guidance formally applies to England and is often adopted elsewhere. In an emergency call 999 anywhere; NHS 111 operates in England, Scotland and Wales, while in Northern Ireland contact your GP or out-of-hours service. Carer support and charging rules differ by nation.

Frequently asked questions

Should I correct someone with dementia who is hallucinating?

Usually not. The experience feels real to them, so contradicting it tends to increase fear. Acknowledge the emotion, reassure them they are safe, check for real hazards and gently redirect to another activity. If the hallucination is not distressing, for example a friendly pet, it may be kinder simply to let it pass.

Can a urine infection cause hallucinations in dementia?

Yes. Infections, including urine and chest infections, are a common cause of delirium, and NICE lists hallucinations among the signs of delirium. A sudden change over hours or days needs prompt medical attention. The NHS says to call 999 or go to A&E if someone suddenly becomes confused.

Which type of dementia causes hallucinations?

Visual hallucinations are a typical symptom of dementia with Lewy bodies, often appearing early, and are also seen in Parkinson’s disease dementia. They can occur in Alzheimer’s and other dementias too, usually in later stages. Sight loss can cause a separate condition, Charles Bonnet syndrome, which produces visual hallucinations without other mental health causes.

Are antipsychotics safe for hallucinations in dementia?

NICE guideline NG97 says antipsychotics should only be offered if someone is at risk of harm or severely distressed, at the lowest dose for the shortest time, reviewed at least every 6 weeks. In Lewy body and Parkinson’s disease dementia they can cause severe sensitivity reactions, so prescribers must know the diagnosis.

Why does my mum think people are stealing from her?

Accusations of theft are a common delusion in dementia. When someone cannot remember moving an item, the explanation that makes most sense to them is that someone took it. Help search, keep spares of frequently lost items, warn carers in advance and avoid arguing. Investigate properly if something genuinely seems to be missing.

When should I call 999 for dementia hallucinations?

Call 999 if hallucinations or confusion come on suddenly, if the person is very drowsy, has difficulty speaking, has a high temperature, or if anyone is at immediate risk of harm. For gradual changes, book a GP appointment. If you are not sure how urgent it is, call NHS 111 for advice.

Sources

• NHS: Dementia with Lewy bodies
• NHS: Symptoms of dementia
• NHS: Charles Bonnet syndrome
• NHS: Confusion (sudden confusion)
• NHS: Free NHS eye tests and optical vouchers
• NICE NG97: Dementia, assessment, management and support
• NICE CG103: Delirium, prevention, diagnosis and management

General information, not legal or financial advice. Figures for 2026/27, checked October 2026.

Reviewed by The Care Panel team on 29 October 2026. This guide is general information about care in England, not legal, medical or financial advice. Rules and rates change; check with your council or an adviser before making decisions.