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What are delusions?

Delusions are false and irrational beliefs that someone holds onto, even when there is evidence that they are not real. Delusions occur in some mental illnesses and may need to be treated by a health professional

Delusions are fixed beliefs about something that are not based in reality, and that others in the same culture, religion or other social group do not share. For example, someone might believe they are the captain of the Australian rugby team, or that an alien has taken over the body of someone in their family.

No facts or reasoning can shake the person's belief. The delusion seems entirely real to them, and they can become completely preoccupied with it.

Not everyone who has delusions has a mental illness. Some people in society have very strong and unusual ideas. But when these ideas become distressing or interfere with day-to-day life, work or relationships, they can be the sign of a mental illness that needs professional treatment.

Delusions may indicate someone has psychosis, schizophrenia, a mood disorder, a personality disorder, dementia or Parkinson's disease.

What are the types of delusions?

There are several different types of delusion:

  • Grandiose delusions: the person believes they are very talented, rich or influential
  • Paranoid delusions: the person believes others want to harm them or are persecuting them
  • Somatic delusions: the person believes there is something wrong with a part of their body, or that part of them is missing
  • Reference delusions: the person believes other people's thoughts or actions are directed towards them, or that special messages are being sent to them via the TV or radio
  • Bizarre delusions: the person believes in something that is physically impossible
  • Delusional jealousy: the person believes their partner is being unfaithful, even when that's impossible
  • Misidentification syndrome: the person believes someone they know has been replaced by an imposter who looks identical to that person

How are delusions treated?

The first step is to see a doctor. The doctor may refer the person to a mental health professional to diagnose the cause of the delusions. The choice of health professional to treat delusions will depend on their cost, where the patient lives and what sort of mental illness is involved. The doctor will be able to advise about this.

Medicines are often used to control delusions, including antipsychotic medicines, antidepressants and mood stabilisers. Other therapies like cognitive behaviour therapy are also sometimes used.

If someone you know is having delusions, remember that they will seem very real to that person. It is best not to argue with them, try to persuade them with evidence, or to laugh at them. You can help by showing them love and support, helping them to recognise what triggers their delusions, and encouraging them to seek treatment.

Where can I find help?

If someone has tried to harm themselves or someone else, or you think they are about to, call triple zero (000) immediately and ask for an ambulance.

A crisis assessment and treatment team (CATT) responds to urgent requests to help people in mental health crisis 24 hours a day, 7 days a week. You can call the mental health crisis line in your state for help.

Read about 'first aid' for psychosis in this Mental Health First Aid fact sheet.

In the longer term, family and friends may become involved in supporting someone who has psychosis. SANE Australia has more information.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: April 2021

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