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What is delirium?

Delirium is a common medical problem that is characterised by changes in mental function and occurs more often among older people. When delirium occurs people are confused and may be either very agitated or quiet and drowsy.

The onset of delirium is always sudden, developing over hours or days, and can last a few days or sometimes weeks.
Delirium occurs often among older people, but it can occur at any age. If delirium is not resolved quickly, it can lead to serious complications such as falls, pressure ulcers, and longer lengths of stay in hospital.

Who is at risk?

People who:

  • are very sick and frail
  • have cognitive impairment or dementia
  • are 65 years of age or older
  • aboriginal and Torres Strait Islander people 45 years or older
  • suffer from depression
  • have poor eyesight or hearing
  • take multiple medications
  • do not drink or eat a lot
  • are having a surgical procedure (e.g. heart, hip or neuro surgery)
  • need help with activities like showering, walking or toileting
  • have had a delirium before.

How common is Delirium?

About 1 in 5 older people admitted to hospital, and about half of the residents in aged care facilities, experience
delirium at some stage of their care. Delirium may occur at any age.

What are the symptoms of delirium?

Symptoms for delirium occur suddenly, and involve changes to a person’s physical and mental state.
Someone with delirium may:

  • appear confused and forgetful
  • unable to pay attention
  • act different from their usual self
  • be very agitated, or very drowsy or both
  • be unsure of the time of day or location
  • changes in their sleeping patterns (staying awake at night and drowsy during the day)
  • have changes in their physical function (e.g. mobility, ability to self-care)
  • feel fearful, upset, irritable, angry or sad
  • see things that are not there (hallucinations)
  • concerned that other people are trying to harm them
  • difficulty to read or write
  • lose control of their bladder or bowels (incontinence)
  • become aggressive.

What causes delirium?

Delirium if often associated with an underlying physical illness or infection. Other common causes of delirium in
older people include:

  • infections (e.g. urinary or chest infections)
  • side effects of medications, including ‘over the counter’ medicines
  • severe pain
  • constipation or not able to empty bladder
  • dehydration or malnutrition
  • withdrawal from alcohol or medications (sleeping tablets or opioids).
  • major surgery
  • any serious illness
  • changes in a person’s environment, such as being hospitalised.

How is delirium treated?

Staff will do a thorough medical assessment to look for and treat the underlying cause of the delirium. If a physical problem is identified, appropriate treatment will be given (e.g. antibiotics commenced to treat a urinary tract infection).
The cause of delirium is not always possible to identify. Treatment is sometimes aimed at lessening symptoms and reducing the risk of complications.

Will delirium happen again?

People who have experienced delirium do have a higher risk of experiencing delirium again. Role of family and carers
It is reassuring for someone with delirium to see familiar people. Family and carers are encouraged to stay and can be provided with meals and a recliner for their comfort.

  • Family members/carers can provide valuable information to the staff caring for the person with delirium.
  • Families are often first to notice delirium, so it is important to notify staff immediately if you notice any change in the person’s mental, behavioural or physical condition.

How to help care for someone with delirium?

Have someone they know well stay with them to provide reassurance.

  • Speak slowly in a clear voice. Identify both yourself and the person by name.
  • Let staff know of any personal information that may help calm and orient the person (e.g. names of family and friends, hobbies, significant events, etc).
  • Help maintain a quiet and peaceful setting.
  • Remind the person where they are, date and time.
  • Bring in familiar objects from home (e.g. photos, a dressing gown, a radio or favourite music).
  • Avoid getting into an argument.
  • Encourage them to eat and drink so they are not hungry.
  • Make sure the lighting is good and not too bright. Open curtains during the day.
  • If the person wears glasses or hearing aids, help to put them on and ensure they are clean and working. Visual or hearing impairment can make confusion worse.
  • Keep your loved one mobile as much as possible. Talk to the nurse or doctor about safe options to prevent them from falling.
  • If the person is agitated or aggressive, do not try to restrain them.

If you have any concerns or question about delirium, talk to your local doctor or ask the hospital staff.


Carers Queensland
1800 242 636

My Aged Care Contact Centre
1800 200 422

National Dementia Helpline
1800 100 500

Alzheimer’s Australia

Mater acknowledges consumer consultation in the development of this patient information.
Mater Doc Num: PI-CLN-420144
Last modified 07/9/2020.
Consumers were consulted in the development of this patient information.
Last consumer engagement date: 05/5/2020
For further translated health information, you can visit healthtranslations.vic.gov.au/ supported by the Victorian Department of Health and Human Services that offers a range of patient information in multiple languages.
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