Delusions

Overview

A delusion is a strong belief that is not true and does not fit with the person's culture or background. The person holds on to it even when there is clear proof it is not real. For example, someone may feel certain that neighbours are plotting to harm them, that the television is sending messages meant only for them, or that a partner is being unfaithful with no evidence. A delusion feels completely real to the person having it, so arguing with the facts usually does not help. Delusions are a symptom, not a condition on their own. They can happen with several mental health conditions, and also with physical illnesses, some medicines, poor sleep, and drug or alcohol use.

Delusions are not rare. They can happen with several mental health conditions and with some physical illnesses. They are also more likely during severe stress, very poor sleep, high fever, or after using drugs or alcohol. Many people have had a delusion at some point without it meaning they have a long-term mental health condition.

Delusions can affect anyone at any age. They are more common in people who already have a mental health condition such as schizophrenia, bipolar disorder, or severe depression. They also happen in older adults with dementia or with sudden confusion from an infection. Children can be affected too, though this is less common. Delusions themselves are not a sign of weakness or a character flaw.

Symptoms

Common symptoms

• A strong belief that others are trying to harm, spy on, follow, or poison you
• Feeling that ordinary events, songs, or TV or radio messages are personal messages meant only for you
• Believing you have special powers, a special mission, or that you are someone famous
• Believing a partner is unfaithful without any evidence
• Believing your thoughts or body are being controlled by outside forces
• Believing you have a serious illness even though medical tests say you are well
• Feeling that familiar people or places have been replaced by copies or impostors
• Being very suspicious, secretive, withdrawn, or easily agitated
• Talking about the belief often, or getting angry or upset when it is questioned
• Changes in sleep, appetite, energy, or interest in daily life alongside the belief

Symptoms in children

• A fixed belief that does not fit the child's age or family culture and does not go away
• Talking about being watched, followed, or controlled by others
• Hearing or seeing things that others do not notice
• A sudden change in behaviour: becoming fearful, withdrawn, or very angry
• Falling school performance or refusing to go to school
• Note: young children often have vivid imaginations. A rich fantasy life is normal. What matters is a belief that stays fixed, causes distress, and gets in the way of daily life.

Symptoms in older adults

• Sudden confusion with false beliefs can be delirium, which is a medical emergency and needs same-day care
• Believing that belongings have been stolen, which is often linked to memory loss in dementia
• Believing that a partner or carer is an impostor or is harming them
• Suspicion that can be made worse by poor hearing or eyesight, or by being in an unfamiliar place
• Delusions triggered by infection, dehydration, constipation, pain, or a new medicine
• Withdrawal, fearfulness, or refusing help with daily care

Causes

Main causes

• Mental health conditions such as schizophrenia, bipolar disorder, severe depression, or postpartum psychosis after childbirth
• Delirium: sudden confusion caused by infection, dehydration, pain, or a hospital stay
• Dementia and other brain conditions, such as stroke or Parkinson's disease
• Drug or alcohol use, and withdrawal from alcohol or sedatives
• Side effects of some prescription medicines, especially in older adults
• Severe sleep deprivation
• Physical problems such as high fever, thyroid problems, low vitamin levels, or kidney and liver problems
• Brain injury or a brain tumour (much less common)
• Extreme stress, grief, or trauma can be a trigger

Risk factors

• A family history of mental health conditions
• Already having a mental health condition
• Older age, memory problems, or dementia
• Hearing or vision loss, which can add to confusion and suspicion
• Social isolation and loneliness
• Heavy or long-term alcohol or drug use
• Long-term poor sleep
• A recent childbirth (postpartum psychosis is rare but serious)
• Certain medical conditions and some medicines

When to see a doctor

See a doctor urgently if:

• A delusion that appeared suddenly or is getting worse quickly
• Delusions with confusion, fever, or a new physical illness
• Any thoughts of self-harm or of harming others — call your local emergency number straight away
• The person has stopped eating, drinking, or taking essential medicines
• You feel unsafe or unable to keep the person safe

Book a routine appointment if:

• You or someone you care for has a fixed belief that is causing distress or problems at home, work, or with friends
• You have noticed growing suspicion, withdrawal, or odd beliefs over weeks or months
• A family member is worried about changes in your thinking or behaviour
• You want to review your medicines because of changes in mood or thinking

Diagnosis

There is no single test for delusions. A doctor will usually start by talking with the person about what they believe, when it started, and how it affects daily life. They will ask about sleep, stress, medicines, alcohol and drug use, and general health. With the person's permission, they may also talk to family or carers, because other people often notice changes first. The aim is to find the cause, since delusions can come from a mental health condition or from a physical problem. The doctor will not argue with the belief. They will try to understand it and check for treatable causes.

Tests that may be done

• A full talk about the person's history, symptoms, and daily life
• Blood tests to check for infection, thyroid problems, vitamin levels, blood sugar, and kidney or liver function
• A urine test to look for infection
• A review of all current medicines, including ones bought over the counter
• Simple memory and thinking checks
• A physical examination, including temperature, blood pressure, and heart rate
• In some cases, a brain scan or a referral to a specialist mental health team
• Sometimes tests for alcohol or drug use

What to expect at your appointment

The assessment may take more than one visit. The doctor may ask the same questions more than once, which is normal. Bringing a family member or friend can help, and it can help to write down what you have noticed and when it started. If a physical cause is found, it is usually treated first. If a mental health condition is likely, the doctor will explain the next steps and offer a referral for specialist care.

Treatment

Treatment depends on the cause. If a physical problem such as an infection, dehydration, or a medicine side effect is behind the delusion, treating that often clears the delusion. If a mental health condition is involved, treatment usually combines talking therapy, support for the person and their family, and sometimes medicine prescribed and monitored by a doctor, usually a psychiatrist. If someone is at risk of harm, a short stay in hospital may be needed to keep them safe while treatment starts. The goal is to reduce distress, keep the person safe, and help them get back to daily life.

Self-care at home

• Keep a simple diary of beliefs, moods, sleep, and medicines, so you can share it with your doctor
• Keep regular routines for sleep, meals, and activity
• Avoid alcohol and street drugs, as they can make delusions worse
• Take any prescribed medicines exactly as your doctor advises, and ask about side effects
• Ask a trusted family member or friend to help you notice changes early
• Try to reduce stress where you can, and build in rest
• Make your home safer if needed, such as limiting access to things that could cause harm, and ask for help to do this
• Keep up hearing aids and glasses, as poor hearing or vision can add to confusion
• Do not argue with the belief. Acknowledging the feeling ('that sounds frightening') often works better than debating the facts

Medical treatments

Doctors treat delusions by treating the cause. This can mean clearing up an infection, correcting dehydration, changing a medicine that is not helping, or helping someone stop alcohol or drugs safely. For mental health conditions, treatment may include talking therapies such as cognitive behavioural therapy, which helps people cope with distressing beliefs and feel more in control. Family therapy and education help the people closest to the person understand what is happening and how to help. Medicines are sometimes used, chosen and monitored by a doctor, usually a psychiatrist. Any medicine is started at a low level and reviewed regularly. The person and their family should be told what the medicine is for, what side effects to watch for, and when to come back.

When is surgery considered?

Surgery is almost never used to treat delusions. Very rarely, if a delusion is caused by a brain problem such as a tumour, a specialist team would discuss whether an operation or other treatment is needed.

Living with this condition

Living with delusions can be frightening for the person and for those around them. It helps to keep days calm and predictable, with regular meals, sleep, and gentle activity. Try not to argue about the belief. Instead, focus on the feeling behind it and on keeping the person safe. Agree on a plan for what to do if things get worse, and share it with close family and friends. Keep a list of contacts and medicines handy. If you are a carer, remember that your own rest and support matter too.

Lifestyle tips

• Keep a regular sleep routine, since poor sleep can make symptoms worse
• Stay connected with people you trust, and avoid long stretches of isolation
• Avoid alcohol and street drugs, and get help if cutting down is hard
• Build gentle daily structure, such as a short walk, a meal routine, and a set time to relax
• Learn your early warning signs, and ask someone close to you to watch for them too
• Join a support group for people with similar experiences, or for carers

Diet and exercise

There is no special diet that treats delusions, but eating regularly and drinking enough water helps your body and mind work well. Dehydration and skipping meals can make confusion worse, especially in older adults. Gentle exercise, like a daily walk, can lift mood and improve sleep. Aim for regular meals with plenty of vegetables, fruit, and whole grains, and limit alcohol. If medicines make you hungry or affect your weight, tell your doctor rather than stopping the medicine yourself.

Mental health and emotional wellbeing

Delusions can be very distressing. Feeling watched, accused, or threatened is exhausting, and it can lead to anxiety, low mood, and loneliness. Many people also feel embarrassed or ashamed afterwards. These feelings are common and understandable, and they are not a sign of failure. Talking therapies can help you manage distress and rebuild confidence. If you ever have thoughts of ending your life, or feel you cannot cope, please reach out for crisis support straight away — speak to your doctor, go to your nearest emergency service, or call your local crisis line or emergency number.

Prevention

Delusions cannot always be prevented, because they can come from many different causes. But some things lower the risk and make episodes easier to manage. Treating physical illnesses early, keeping good sleep, avoiding alcohol and street drugs, and managing stress all help. Having regular medicine reviews, especially in later life, can catch side effects early. Keeping hearing aids and glasses up to date reduces confusion. If you or someone close to you has had delusions before, learning the early warning signs and getting help quickly can make the next episode shorter and milder.

Screening programmes

There is no routine screening test for delusions. Regular check-ups, medicine reviews, and memory checks in older adults can help spot problems early. If you are worried about your thinking or beliefs, you can raise it at any appointment — you do not need to wait for a screening.

Complications

If left untreated

• Ongoing distress, fear, and anxiety
• Low mood and, in some cases, thoughts of self-harm or suicide
• Strain on relationships with partners, family, and friends
• Problems at work, at school, or with money
• Becoming isolated or losing housing
• Refusing needed medical care because of the belief
• Increased use of alcohol or drugs to cope
• Rarely, harm to the person or to others if the belief leads to dangerous actions

Long-term outlook

The outlook is often good, especially with early help. When the cause is found and treated, many delusions improve or go away completely. For people with a longer-term mental health condition, delusions can often be well managed with support, therapy, and sometimes medicine, so that daily life, work, and relationships can carry on. Recovery is not always a straight line, and setbacks can happen, but they do not mean treatment has failed. With the right support, most people find a way forward.

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