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Recognising delirium

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What is delirium?

Delirium is a state of mental confusion. Delirium is not a disease, but a group of symptoms that can be caused by other medical problems.

Delirium can start very suddenly, sometimes in just a few hours. Delirium is very common, particularly in older people and people treated in hospital.

Delirium is not the same as dementia, and it can be treated.

    What are the symptoms of delirium?

    There are three types of delirium: hyperactive delirium, hypoactive delirium, and mixed delirium.

    The symptoms of someone with hyperactive delirium include:

    • Confusion: not being sure where they are, or why they are there, perhaps not being able to remember instructions or names.
    • Distressing thoughts, paranoia, and worry that people are trying to harm them.
    • Hallucinations: seeing or hearing things that aren’t there.
    • Being agitated or restless, and wandering around.
    • Behaving differently: they could become aggressive, or say or do inappropriate things.

    The symptoms of someone with hypoactive delirium include:

    • Not being able to focus: difficulty following a conversation, or being easily distracted.
    • Loss of balance.
    • Loss of appetite.
    • Being sleepy and withdrawn.

    Mixed delirium means that someone can switch between symptoms of hyperactive delirium and hypoactive delirium, sometimes over the course of a day.

      What can cause delirium?

      Medical problems that can cause delirium include:

      • Infection (like a urine or chest infection).
      • Being in pain.
      • Drug withdrawal or alcohol withdrawal.
      • Constipation.
      • Dehydration (not drinking enough).
      • Hypothermia (being too cold).
      • Hyperthermia (being too hot).
      • Being on certain medications.

      Delirium can often be caused by more than one of these things, and sometimes the cause is never found. Someone is also more likely to get delirium if they:

      • Have had surgery.
      • Are more than 65 years old.
      • Already have memory problems (like dementia).
      • Have had a serious injury like a hip fracture.
      • Have problems with sight or hearing.
      • Are staying in an unfamiliar environment, like a hospital.

        How can I recognise delirium in someone who has dementia?

        If someone with dementia has delirium, there will be a sudden, noticeable change in their usual behaviour. This is most often noticed by family members or carers, who know what is normal for that person.

        Someone who has dementia and delirium may do things that are out of character: for example, they may not usually be aggressive, but suddenly start behaving aggressively if they have delirium.

          Can delirium be treated?

          Yes. Delirium is preventable and treatable.

          Doctors treat delirium by treating the cause of the delirium. For example, if a medicine is causing delirium, the doctor will stop or change that medicine. If an infection is causing delirium, they will treat the infection.

          Sometimes, in older people, the effects of delirium can last a bit longer even after the cause is treated, even weeks or months. Remembering the delirium can also be upsetting and frightening for that person.

          The earlier that delirium is identified and treated, the better the outcome for that person.

            How can I help to prevent delirium in someone at risk?

            You can help someone by:

            • Making sure they have their hearing aids and glasses.
            • Encouraging them to drink and eat regularly.
            • If they are in hospital, explain where they are and give them familiar things to look at, for example, a bedside clock, a calendar, or some photos.
            • Helping them to sleep by reducing noise and dimming lighting.
            • Making sure they go to the toilet regularly.
            • Helping them to get moving, sit up, or get out of bed.

              Checklist: signs of delirium

              Sometimes the signs of delirium can be difficult to spot. This checklist can help you if you are not sure if someone has delirium.


              Are they confused?

              • If you ask them what year it is, can they tell you?.
              • Can they tell you where they are?.
              • Do they know what your name is?.

              Do they lose focus?

              • Can they hold a conversation with you without being distracted?.

              Are they having distressing thoughts?

              • Do they think someone is trying to hurt them?.

              Are they restless?

              • Are they agitated and don’t want to sit still?.

              Are they lethargic?

              • Are they sleeping a lot more than is normal for them?.

              Are they being aggressive?

              • Has their personality changed?.

              Have they had one or more falls?

              Are they eating and drinking a normal amount for them?

              • Have they lost their appetite?.

              Are they experiencing hallucinations?

              • Are they seeing or hearing things that aren’t there?.
              • Are they having very vivid dreams, which sometimes seem to go on when they’re awake?.

              Have these changes come on suddenly, over hours or days?

                What should I do if I think someone has delirium?

                If that person is in hospital, speak to the nurse or medical professional looking after them. If they are not in hospital, contact your GP.

                The earlier that medical staff recognise delirium and treat it, the better. Don’t be afraid to tell someone if you are worried.

                  This information is intended for patients receiving care in Brighton & Hove or Haywards Heath.

                  The information in this leaflet is for guidance purposes only and is in no way intended to replace professional clinical advice by a qualified practitioner.

                    Publication Date: June 2022

                    Review Date: March 2025

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