Delirium is a medical emergency
In hospital, tell the nurse or doctor straight away if the person seems suddenly confused or not themselves. At home, call 000 or go to an emergency department.
In short: delirium is a sudden change in thinking and behaviour, often triggered by illness, surgery, pain or medicines. It is common in older people after operations, particularly hip fracture surgery. Families can help by telling the team about memory problems in advance, bringing glasses and hearing aids, sharing what is normal for the person, and reporting any sudden change straight away.
What delirium is
Delirium is a sudden disturbance in attention, awareness and thinking. It develops over hours or days, and it tends to come and go during the day, often getting worse at night. healthdirect describes it as a medical emergency: the cause needs to be found and treated, and a person with delirium is at risk of falls and injury. Victoria’s Department of Health notes that it may be the only sign that someone is becoming more unwell.
Delirium usually lasts a few days. In vulnerable older people it can last for weeks or months.
How common it is
- Australia’s Delirium Clinical Care Standard reports that about 10 to 18% of people aged 65 and over have delirium when they are admitted to hospital, and a further 2 to 8% develop it during their stay.
- Victoria’s Department of Health notes that older people in surgical, palliative care and intensive care settings have the highest rates, and that delirium can be prevented in 30 to 40% of cases.
- The Hip Fracture Clinical Care Standard says people with a broken hip are at high risk of delirium.
What it looks like
There are two main forms, and the quiet one is easy to miss. Victoria’s Department of Health notes that the quiet (hypoactive) form is the most common type in older people.
The agitated form
Restless and distressed
- restless, unsettled or irritable
- frightened, upset or angry
- seeing things that are not there
- acting differently from usual
The quiet form
Withdrawn and sleepy
- unusually sleepy or hard to rouse
- quiet, withdrawn or slow to respond
- low or flat in mood
- easily mistaken for tiredness after an operation
In either form, the person may not know where they are or what time it is, may be forgetful, may sleep at odd times, and may lose control of their bladder or bowel.
Delirium is not dementia
| Feature | Delirium | Dementia |
|---|---|---|
| How it starts | Suddenly, over hours or days | Slowly, over months or years |
| Day to day | Comes and goes, often worse at night | Changes slowly over time |
| Outlook | Usually improves when the cause is treated | Gradually gets worse |
The two are linked: people living with dementia are more likely to develop delirium.
Who is at higher risk
- people aged 65 and over, or 45 and over for Aboriginal and Torres Strait Islander people
- people living with dementia, memory problems, an intellectual disability or a brain injury
- anyone who has had delirium before
- people with poor eyesight or hearing
- people who are frail, unwell or less mobile
- people taking several medicines, or whose medicines have recently changed
- people having surgery, particularly hip surgery
- people with depression, or who drink alcohol heavily.
Common triggers
healthdirect lists infection or illness, changes to medicines, severe pain, dehydration or not eating enough, constipation or being unable to empty the bladder, withdrawal from alcohol, cigarettes or sleeping tablets, and the change of surroundings that comes with being in hospital. The cause is not always found.
Before the operation: what families can do
- Tell the team about memory problems or past delirium at the pre-admission or anaesthetic assessment. The Delirium Clinical Care Standard expects the risk of delirium to be identified early, so that prevention can start.
- Share what is normal for the person. Victoria’s Department of Health suggests an “About me” record, with details such as family names, interests and routines, which staff can use to reassure and orientate them.
- Pack glasses and hearing aids, with spare batteries, and check they work.
- Bring an up-to-date list of medicines, including anything for sleep or mood, and say honestly how much alcohol the person drinks.
- Ask about pain relief. Good pain control helps prevent delirium. For a broken hip, the clinical care standard recommends a nerve block unless it is unsuitable, partly because it reduces the need for opioids, which can add to confusion.
In hospital: how families can help
healthdirect and Victoria’s Department of Health suggest:
- Speak slowly and clearly. Introduce yourself, and use the person’s name.
- Gently remind them of the day, the time and where they are, without arguing.
- Make sure they are wearing their glasses and hearing aids.
- Help them to eat and drink, if the staff agree.
- Bring familiar things, such as photos, their own clothes or favourite music.
- Let them walk if they want to and it has been allowed, while keeping them from falling.
- Visit regularly if that calms them, and ask whether you can stay.
- Tell the staff straight away if the person seems different from usual. Family observations matter, because you know what is normal for them.
After going home
Delirium can take time to clear completely. Before discharge, ask for written information about delirium and who to contact with concerns, and make sure the GP knows it happened. If new confusion appears at home, call 000 or go to an emergency department. While you wait, stay with the person, keep them calm and protect them from falls, and be ready to tell the paramedics about their medical history, their medicines and the recent change in behaviour.
For health advice at any time, healthdirect (NURSE-ON-CALL in Victoria) is on 1800 022 222.
Common questions
Is delirium caused by the anaesthetic?
Delirium usually has more than one cause. Surgery, pain, infection, dehydration, constipation, some medicines and the hospital environment can all contribute, especially in someone who is already vulnerable. Ask the anaesthetist and the ward team how they plan to reduce the risk for your relative.
Does delirium mean my mother has dementia?
No. Delirium comes on suddenly and usually clears, while dementia develops slowly over time. People living with dementia are more likely to develop delirium. If you are worried about memory after recovery, talk to the GP.
Can I stay with my father in hospital?
Ask the ward. Familiar faces can be reassuring, and healthdirect notes that families may be encouraged to stay. Victoria's Department of Health guidance suggests families may be offered the option to stay overnight.
Sources
- Australian Commission on Safety and Quality in Health Care. Delirium Clinical Care Standard (2021). Standard updated 2021; accessed 2 Nov 2026.
- healthdirect Australia. Delirium: symptoms, diagnosis and treatment. Last reviewed Sep 2024.
- Victorian Department of Health. Delirium (older people in hospital). Updated 15 Jan 2026.
- Australian Commission on Safety and Quality in Health Care. Hip Fracture Clinical Care Standard (2023). 2023.
- Written by
- Altitude Creative, health content team, on behalf of Dr Walid Aly
- Clinical reviewer
- In progress
- Review date
- Clinical review in progress
- Next review due
- Set at clinical review
How this guide is written, reviewed and corrected: editorial policy.
In an emergency, call 000. This information is general and does not replace advice from your treating practitioner.