Sudden confusion and delirium in older people: what to do

A carer sits close to an older woman who seems drowsy and muddled, holding her hand and offering water.

What delirium is

Delirium is a sudden change in a person’s mental state. Families often describe it simply: “She’s not herself.” It usually develops over hours or a day or two and is often the first sign that someone is becoming physically unwell. Signs include:

being less alert, easily distracted or unable to follow a conversation
not knowing where they are, or mixing up day and night
seeing or hearing things that are not there, or believing things that are not true
sudden restlessness, agitation or uncharacteristic anger
becoming unusually sleepy, withdrawn or quiet
suddenly struggling with things they could do yesterday, such as walking or eating
symptoms that come and go through the day, often worse in the evening

There are three types. Hyperactive delirium is the restless, agitated kind that is easy to spot. Hypoactive delirium makes people quiet, sleepy and withdrawn, and is easily mistaken for tiredness. Mixed delirium switches between the two. In older people, the hypoactive and mixed types are the most common, so a parent who is suddenly drowsy and not eating needs as much attention as one who is agitated.

Delirium or dementia?

	Delirium	Dementia
How it starts	Suddenly, over hours or a day or two	Slowly, over months or years
Day to day	Changes markedly, even hour to hour	Fairly consistent from day to day
Alertness and attention	Often reduced or swinging	Usually normal until the later stages
Outlook	Often improves when the cause is treated	Long-term and progressive
Urgency	A medical emergency	Needs planned support

Someone can have both. Dementia is the biggest single risk factor for delirium, and a person with dementia who suddenly becomes much more confused should be treated as possibly having delirium until a clinician has checked.

Common causes of sudden confusion

Delirium is usually the brain’s reaction to another problem, and there is often more than one cause. The NHS, the Alzheimer’s Society and Dementia UK list:

Infections, especially urine and chest infections.
Dehydration and not eating enough.
Constipation or being unable to pass urine.
Pain, which people with dementia may not be able to describe.
Medicines: a new medicine, a changed dose, or several medicines together, particularly strong painkillers and sedatives.
Surgery, especially hip surgery, and anaesthetics.
Stroke or mini-stroke (TIA), a head injury after a fall, or low blood sugar in people with diabetes.
Alcohol, or stopping alcohol suddenly.
Low oxygen from lung or heart problems.
Unfamiliar, noisy or poorly lit places, such as a hospital ward, and poor sleep.

The NHS also warns about carbon monoxide poisoning, especially if other people in the home feel unwell too.

When to call 999, NHS 111 or the GP

Two paramedics kneel beside an older man in his armchair while his wife holds his hand. Call 999 or go to A&E if someone suddenly becomes confused. The NHS treats sudden confusion as an emergency because some causes, such as a stroke or a serious infection, can be life-threatening. The person must not drive themselves: call an ambulance or ask someone to drive them.

Call 999 straight away if they also:

are very drowsy, hard to wake or have difficulty speaking
show signs of a stroke: face drooping, arm weakness or slurred speech
have blue, grey, pale or blotchy skin, lips or tongue, cold skin, or are breathing fast or struggling to breathe
have fallen and may have hurt their head

Ask for an urgent GP appointment or call NHS 111 (free, 24 hours) if you are unsure, or if:

they are 65 or over and have symptoms of a urine infection
they seem dehydrated: dark urine, peeing less, dizziness on standing that does not go away, or unusual tiredness
they are a little more muddled than usual and you cannot tell whether it is sudden

Book a routine GP appointment for changes in memory or thinking that have come on gradually. That is a different problem and needs a planned assessment.

What to say when you call

“My father is 84 and has dementia. Since yesterday afternoon he has become much more confused than his normal and very sleepy. Normally he knows who I am, walks with a frame and chats. He’s had a temperature since this morning and hasn’t drunk much. He takes [number] medicines and started a new one on [date].”

Have ready:

a list of their medicines, or the packets, including any new or changed ones
what is normal for them, and when the change started
any recent fall, illness, operation, constipation or change in drinking
their NHS number and GP surgery
any advance care plan, “about me” sheet or Lasting Power of Attorney

While you wait for help

The NHS advises:

Stay with them, tell them who you are and where they are, and keep reassuring them.
Use simple words and short sentences.
Do not ask lots of questions while they are confused.
Do not stop them moving around unless they are in danger.
Gather their medicines to take with you.

Helping someone with delirium in hospital

A woman helps her father put on his glasses in his hospital bed, a family photograph beside him. Familiar people make a real difference. NICE recommends regular visits from family and friends as part of preventing and managing delirium. Since April 2024, hospitals in England have been required by CQC Regulation 9A to support visiting, so ask the ward how you can be there, especially at mealtimes and in the evening.

Tell staff clearly what the person is normally like. They have only seen them unwell.
Bring glasses, hearing aids (with batteries), dentures and familiar things such as photographs.
Help them eat and drink, and keep a note of how much.
Remind them gently where they are and why, without arguing.
Ask what is causing the delirium and what is being done about it.

If you feel the person is getting worse and your concerns are not being acted on, ask for an urgent review. Under Martha’s Rule, being introduced across acute hospitals in England, families can call a dedicated hospital number to ask for a rapid review by a different team. Each hospital has its own number: look for posters on the ward or ask staff. You might say:

“I’m worried my mother is getting worse. This is not her normal. I’d like to ask for a Martha’s Rule review.”

Recovery at home after delirium

Recovery can take days, weeks or sometimes months. Expect good and bad days. At home:

Keep the routine calm and familiar, with daylight, regular meals and drinks, and good sleep.
Encourage gentle activity as soon as it is safe.
Ask the GP for a follow-up, including a review of medicines.
If memory or thinking has not returned to normal after a few weeks, ask the GP whether a memory assessment is needed.
Ask about reablement if they are less able than before.

See our guide to leaving hospital for help with the journey home.

Lowering the risk of delirium at home

Based on NICE’s recommendations for people at risk:

Drinks within reach all day, and help to drink at mealtimes. Pale urine is the aim.
Regular meals, fibre and fluids to prevent constipation.
Glasses clean and worn, hearing aids working.
A clock and calendar easy to see, and a calm, well-lit home.
Daily movement, even seated exercises.
A regular bedtime and a quiet night.
Pain asked about and treated, including in people who cannot say they are in pain.
A medicines review with the GP or pharmacist, especially for anyone on several medicines.
Infections treated promptly.

People most at risk, according to NICE, are those aged 65 or over, people with memory problems or dementia, people with a hip fracture and people who are severely ill. Poor sight or hearing and a previous episode of delirium add to the risk.

Where to get support

NHS 111: free, 24 hours, by phone or online.
Dementia UK Admiral Nurse Dementia Helpline: 0800 888 6678 (free). Monday to Friday 9am to 9pm, weekends 9am to 5pm.
Alzheimer’s Society Dementia Support Line: 0333 150 3456. Monday to Wednesday 9am to 8pm, Thursday and Friday 9am to 5pm, weekends 10am to 4pm.
Age UK Advice Line: 0800 678 1602 (free). 8am to 7pm, every day of the year.

What to do next

Write a short “what’s normal for Mum” note and keep it with the medicines list.
Learn the signs of a urine infection and dehydration in older people.
Make sure drinks, glasses and hearing aids are part of every day.
Ask the GP or pharmacist for a medicines review if several medicines are taken.
If someone suddenly becomes confused, call 999 or go to A&E.

How we can help

A carer who sees someone every day is often the first to notice that they are “not themselves”. Day and Nightcare provides home care visits from one hour, waking nights and sleep-ins across Oxfordshire, and 24-hour care with carers working in shifts anywhere in England, and fully managed live-in care anywhere in England from £1,550 a week, including support after a hospital stay. Call us on 01865 715780 to arrange a free assessment.

Common questions

Why do doctors keep asking what my parent is normally like?

Because delirium is recognised by comparing the person with their usual self. Staff in A&E or on a ward have only ever seen them unwell, so they may not know that a quiet, muddled, sleepy person is normally chatty and sharp. NICE asks clinicians to look for recent changes reported by the person, a carer or a relative. Telling staff clearly what has changed, and when, is one of the most useful things a family can do.

How long does delirium last?

Usually days, but sometimes longer. The Alzheimer's Society says symptoms often improve within a few days of the cause being treated, though serious infections can take longer, and some people, particularly older people after major surgery, take weeks or months to get their memory and thinking back. In people who already have memory problems, prolonged or severe delirium can speed up decline. Delirium does not itself cause dementia.

Can a urine infection cause confusion in older people?

Yes. The NHS says older or frail people and people with dementia with a urinary tract infection may become agitated or confused, leak urine more than usual, or have new shivering or shaking. Anyone aged 65 or over with symptoms of a urine infection should have an urgent GP appointment or call NHS 111. Call 999 if they are confused, drowsy or having difficulty speaking. But not all confusion is a urine infection, so do not assume: let a clinician look for the cause.

How common is delirium in hospital?

Very common. NICE says about 20% to 30% of people on medical wards in hospital have delirium, and between 10% and 50% of people having surgery develop it. Older people, people with dementia, people with a hip fracture and people who are severely ill are most at risk. It is often missed, especially the quiet, sleepy kind, which is why families who know what the person is normally like have such an important role.

What is the 4AT test?

The 4AT is a short screening test, taking about two minutes, that doctors and nurses use to help spot delirium. The Alzheimer's Society explains that it covers four things: how alert the person is, whether they know basic facts such as their age and where they are, whether they can concentrate on a simple task, and whether there has been a sudden change. It supports a clinician's judgement rather than replacing it, and your account of the change matters.

Sources and further information

Prepared by the Day and Nightcare care team. Last updated 30 October 2026; sources last checked 30 October 2026. This guide is general information about care in England, not financial, legal or medical advice.