This information is for anyone who has experienced delirium, knows someone with delirium or is looking after people with delirium.


This webpage provides information, not advice. You should read our full disclaimer before reading further.

This information reflects the best available evidence at the time of writing. We aim to review our mental health information every three years, and update critical changes more regularly.

©  October 2015 Royal College of Psychiatrists 

Delirium is a state of mental confusion that can happen if you become medically unwell.  It is also known as an 'acute confusional state'.

Medical problems, surgery and medications can all cause delirium. It often starts suddenly and usually lifts when the condition causing it gets better. It can be frightening – not only for the person who is unwell, but also for those around him or her.

You may:

  • Be less aware of what is going on around you.
  • Be unsure about where you are or what you are doing there.
  • Be unable to follow a conversation or to speak clearly.
  • Have vivid dreams, which are often frightening and may carry on when you wake up.
  • Hear noises or voices when there is nothing or no one to cause them. 
  • See people or things which aren’t there.
  • Worry that other people are trying to harm you.
  • Be very agitated or restless, unable to sit still and wandering about.
  • Be very slow or sleepy.
  • Sleep during the day, but wake up at night
  • Have moods that change quickly. You can be frightened, anxious, depressed or irritable.
  • Be more confused at some times than at others – often in the evening or at night.

You can help someone with delirium feel calmer and more in control if you:

  • Stay calm.
  • Talk to them in short, simple sentences. Check that they have understood you. Repeat things if necessary.
  • Remind them of what is happening and how they are doing.
  • Remind them of the time and date. Make sure they can see a clock or a calendar.
  • Listen to them and reassure them.
  • Make sure they have their glasses and hearing aid.
  • Help them to eat and drink.
  • Try to make sure that someone they know well is with them. This is often most important during the evening, when confusion often gets worse.
  • If they are in hospital, bring in some familiar objects from home.
  • Have a light on at night so that they can see where they are if they wake up.
  • About 2 in 10 hospital patients have a period of delirium.
  • Delirium is more common in people who:
    • are older
    • have memory problems

    • have poor hearing or eyesight

    • have recently had surgery

    • have a terminal illness

    • have an illness of the brain, such as an infection, a stroke or a head injury.

The most common causes of delirium are:

  • a urine or chest infection
  • having a high temperature
  • side-effects of medicine like pain killers and steroids
  • dehydration, low salt levels, low haemoglobin (anaemia)
  • liver or kidney problems 
  • suddenly stopping drugs or alcohol
  • major surgery
  • epilepsy
  • brain injury or infection
  • terminal illness
  • constipation
  • being in an unfamiliar place.

There is often more than one cause – and sometimes the cause is not found.

If someone suddenly becomes confused, they need to see a doctor urgently. The person with delirium may be too confused to describe what has happened to them, so it's important that the doctor can talk to someone who knows the patient well.

To treat delirium, you need to treat the cause.  For example, an infection may be treated with antibiotics.

Sedatives can make delirium worse, so should only be used in a few situations:

  • When someone who drinks a lot of alcohol stops suddenly, they will need a regular dose of a sedative medication (benzodiazepines) that is reduced over several days. This will stop withdrawal symptoms, but should be done under close medical supervision.
  • To calm someone enough to have investigations or treatment.
  • To stop someone endangering themselves or other people.
  • When someone is very agitated or anxious.
  • When someone is seeing or hearing things that are not there.

Low doses of antipsychotic medication should be given to help with frightening hallucinations or beliefs that people are trying to harm you.

Any sedative medication should be given in the lowest possible dose for the shortest time possible.

Delirium gets better when the cause is treated. 

You can recover very quickly, but it can take several days or weeks. 

People with dementia can take a particularly long time to get over delirium.

You may not remember what has happened, particularly if you had memory problems beforehand. 

However, you may be left with unpleasant and frightening memories – and even worry that you are going mad.

It can be helpful to sit down with someone who can explain what happened.This might be a family member, a carer or your doctor. They can go through a diary of what happened each day. 

Most people feel relieved when they understand what happened and why.

You are more likely to have delirium again if you become medically unwell. 

Someone needs to keep an eye out for the warning signs that you are getting unwell again – whatever the original cause was.

If they are worried they should get a doctor as soon as possible. If medical problems are treated early, this can prevent delirium from happening again.

European Delirium Association

An organisation for health professionals and scientists involved with delirium.  The website also has links to other websites that have information on delirium for health professionals, patients and carers.

Royal College of Physicians

The prevention, diagnosis and management of delirium in older people - national guidelines.  Royal College of Physicians.  2006.   Guidelines for health professionals working with people with delirium.

Prevent delirium video

The delirium awareness video, I can prevent delirium, was produced by Faculty of Old Age Psychiatry members, Dr Krishnan and Dr Bennett, in collaboration with Teesside local councils and CCG to improve awareness of delirium as part of #icanpreventdelirium campaign and conference.

  • NICE Guidelines CG103 (2010). Delirium:diagnosis, prevention and management
  • Clinical management and prevention of delirium.  Marcantonio ER.  Psychiatry (2008);7: 42-48.
  • Delirium.  Brown B & Boyle M.  In: ABC of Psychological Medicine (2003).  BMJ Books.
  • Drug treatment of delirium: Past, present and future.  Bourne RS et al.  Journal of Psychosomatic Research (2008);65:273-282.
  • The delirium experience: a review.  O’Malley G et al.  Journal of Psychosomatic Research (2008);65:223-228.
This factsheet was produced by the RCPsych's Public Education Editorial Board.
Series Editor: Dr Philip Timms

Original authors: Dr Hilary Gordon, Professor George Ikkos , Dr Susie Lingwood and Dr Jim Bolton.