Confusion and delirium assessment
An urgent check to work out why an older person has suddenly become confused, and to find and treat the cause.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- Sudden new confusion in an older person is delirium until proven otherwise — and it is a medical emergency that needs urgent assessment, not 'just old age'.
- The assessment looks for a cause (commonly infection, dehydration, constipation, pain or a new medicine); treating it often reverses the confusion.
- Delirium is different from dementia: it starts suddenly and fluctuates, whereas dementia develops slowly.
- Family and carers who know the person are often the first to notice the change — say clearly 'this is new and sudden' when you seek help.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your psychiatrist will give you advice for your situation.
Finds treatable causes such as infection, dehydration or constipation, so the confusion can often be reversed.
A bedside delirium screen is not a substitute for examining and treating the underlying illness — it cannot replace medical assessment of a sick patient.
Observations and bedside tests are done, urgent causes looked for, and treatment of an obvious cause (such as fluids or antibiotics) may begin.
A clearly identified, treated cause and a written plan the family understands.
Observations and bedside tests are done, urgent causes looked for, and treatment of an obvious cause (such as...
Blood and urine results come back and help confirm or narrow the cause. The person is kept calm, oriented and...
As the cause is treated, confusion often starts to lift. Sleep and alertness may still swing, with worse evenings...
Many people recover over days to a few weeks. Some, especially the very frail or those with dementia, take longer...
What is a confusion and delirium assessment?
Delirium means becoming suddenly confused, muddled or 'not yourself' over hours or a day or two. It is very common in older people, especially in hospital or when unwell, and it is a medical emergency that needs the cause found and treated.
A confusion and delirium assessment is the set of checks a doctor or nurse does to confirm whether someone has delirium, and to hunt for what is causing it — often an infection, dehydration, constipation, pain, a new medicine, or low oxygen or blood sugar. Several causes can act together.
Delirium is not the same as dementia. Dementia comes on slowly over months or years; delirium comes on suddenly and the level of alertness often swings through the day. Importantly, delirium is frequently reversible once the cause is treated — so finding the cause matters enormously.
This assessment cannot, on its own, tell you whether someone also has dementia. That is a separate question, usually looked at later once the person has recovered from the acute illness.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Delirium versus dementia
| Feature | Delirium | Dementia |
|---|---|---|
| How it starts | Suddenly, over hours or days | Slowly, over months or years |
| Alertness | Often drowsy or swinging through the day | Usually steady and alert |
| Reversible? | Often, once the cause is treated | Not usually; it is progressive |
| What it signals | A new physical illness or trigger | An ongoing brain condition |
The two often overlap — someone with dementia can develop delirium on top, and is at higher risk of it. A sudden change always needs urgent assessment.
Preparing for your test
- If you can, bring someone who knows the person well, or be ready to describe by phone how they normally are and exactly when they changed.
- Bring a full, up-to-date list of all medicines, including anything recently started, stopped or bought over the counter.
- Note any recent illness, falls, fever, cough, pain, poor drinking, constipation or difficulty passing urine.
- Bring glasses and hearing aids — being unable to see or hear makes confusion much worse and can mimic it.
- Mention any known dementia, previous delirium, alcohol use or recent changes in routine or surroundings.
- Write down questions you want answered, as the situation can move quickly and feel overwhelming.
What happens
A doctor or nurse will talk to the person and, crucially, to someone who knows them, to establish what is normal for them and exactly when things changed. They will do a short structured cognitive check (often the 4AT), measure temperature, pulse, blood pressure, oxygen and blood sugar, and examine for infection, dehydration, a full bladder or constipation.
They will usually take blood and a urine sample, and may arrange a chest X-ray, an ECG or — less commonly — a brain scan if there is a specific reason, such as a head injury or new weakness. They will review every medicine the person is taking.
The aim throughout is to confirm whether this is delirium and, most importantly, to find and treat the cause. The person should be cared for calmly, with familiar faces, good lighting, their glasses and hearing aids, and help with eating and drinking.
Is this test right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- A bedside delirium screen is not a substitute for examining and treating the underlying illness — it cannot replace medical assessment of a sick patient.
- It is not the right tool to diagnose dementia; that needs a separate assessment once the person has recovered.
- If the person is acutely and severely unwell (for example drowsy, very low oxygen or signs of sepsis), they need emergency care rather than an outpatient assessment.
- It will not give meaningful results if reversible barriers like missing glasses, hearing aids or language support are not addressed first.
Delay or rearrange if…
- Do not delay — sudden confusion should be assessed the same day; the only 'delay' is reserving formal cognitive testing until the acute illness settles.
- Formal dementia assessment should wait until the person has fully recovered from the delirium, as results during illness are misleading.
- If the person is too drowsy or distressed to take part, stabilise and treat first, then reassess.
- Avoid relying on a single snapshot; alertness fluctuates, so reassessment over time is part of the process.
Alternatives to discuss
- Specialist tools such as CAM-ICU are used instead of the 4AT in intensive care or recovery after an operation.
- Where the cause is obvious and the person is well enough, treating the cause and monitoring at home may be appropriate.
- A comprehensive geriatric assessment for frail older people, which looks more broadly at health, medicines and function.
- A later, separate memory clinic assessment if dementia is the real concern.
- Watchful waiting with carer support for very mild, clearly resolving confusion, with a clear plan to escalate.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Benefits
- Finds treatable causes such as infection, dehydration or constipation, so the confusion can often be reversed.
- Distinguishes a sudden, reversible problem (delirium) from a slow one (dementia), which changes what happens next.
- Picks up serious illness early, when the only sign may be new confusion.
- Reduces the chance of harm by getting the person into a calm, safe, well-supported setting.
- Gives families an explanation and a plan, rather than 'it's just their age'.
Risks & complications
- The assessment itself is gentle, but tests like blood draws cause brief discomfort or bruising.
- The cause is not always obvious straight away, and the person may need to be watched over a day or two.
- More than one cause is often present, so treatment may need several steps.
- An unnecessary or repeated scan if the reason for it is not clearly thought through.
- Confusion being wrongly put down to dementia or 'old age', so a treatable cause is missed.
- Sedating medicines used too readily, which can make delirium worse.
- A serious underlying illness (such as severe infection or a stroke) that needs urgent hospital treatment.
- Delirium that does not fully clear, especially in someone who is very frail or has dementia.
The biggest risk is not the assessment but a missed or delayed diagnosis — sudden confusion being dismissed as 'just old age' or assumed to be dementia. The other key risk is over-sedation: medicines to calm someone should be a last resort, because they can deepen delirium and cause falls. Ask: what is the suspected cause, what is being done about it, and what should we watch for.
Published figures to discuss
Delirium is extremely common in unwell older people but figures vary hugely with the setting, the underlying illness and how it is looked for. Hypoactive (quiet, withdrawn) delirium is easily missed, so reported rates depend heavily on whether it is actively screened for. We have therefore kept this qualitative rather than quoting precise percentages.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Delirium missed as 'just dementia' | Common and dangerous | Sudden confusion, fluctuating alertness or new hallucinations are medical red flags. | Guide sourcesClinical context |
| Underlying cause untreated | Potentially serious | Infection, dehydration, constipation, urinary retention, pain, hypoxia, stroke and medicines are common triggers. | SIGN 157 — Risk reduction and management of deliriumsign.ac.ukSource-linked context |
| Sedating medication worsens confusion or falls | Higher in older adults | Antipsychotics or benzodiazepines should be used cautiously and only when necessary for safety. | Guide sourcesClinical context |
| Functional decline after delirium | Common recovery issue | Delirium can take weeks to improve and should trigger follow-up for cognition, mobility and carer support. | Guide sourcesClinical context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no physical recovery from the assessment itself. What matters is how the person recovers once the cause of the delirium is treated — and this can take longer than families expect.
- Confusion that swings through the day and is worse in the evening or at night.
- Tiredness, disturbed sleep and vivid dreams while recovering.
- Patchy memory of the confused period afterwards, which is normal.
- A gradual, sometimes bumpy return to normal rather than a sudden switch.
Aftercare
- Keep treating the underlying cause exactly as advised (for example finishing antibiotics or keeping up fluids).
- Keep the person in calm, familiar surroundings with good lighting and a clear day–night routine.
- Make sure glasses and hearing aids are worn, and encourage regular drinking and eating.
- Encourage gentle movement and getting up and dressed in the day to aid recovery.
- Review any sedating medicines with the clinician and stop them as soon as it is safe.
- Watch for the confusion coming back, which can signal the illness returning or a new problem.
- Arrange a memory review later if concerns persist once the person has fully recovered.
- A written note of the suspected cause and the treatment plan
- Clear instructions on any new medicines and when to stop them
- A named contact or number to call if confusion worsens
- Glasses, hearing aids and familiar items kept within reach
- A simple drinking and eating routine agreed
- A plan for who reviews recovery and when
⚠ Get urgent help if…
- Any sudden new confusion in an older person — treat as urgent and seek help the same day.
- Drowsiness that is hard to rouse, or the person becoming difficult to wake.
- A high temperature, shaking chills, or looking very unwell.
- New weakness, slurred speech, facial droop or a severe headache (possible stroke — call 999).
- Not passing urine, severe tummy pain, or signs of dehydration such as not drinking.
- Severe agitation that puts the person or others at risk.
- Confusion that keeps worsening despite treatment of the suspected cause.
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your psychiatrist gives you.
Results & realistic expectations
A good outcome is that the cause of the delirium is found and treated, and the person gradually returns to how they were before. Because delirium is often reversible, identifying the trigger is the single most useful result.
The assessment cannot promise full recovery, and it cannot by itself diagnose or rule out dementia. If memory or thinking problems remain once the acute illness has cleared, that needs looking at separately, when the person is well enough for a fair assessment.
An episode of delirium is a marker of vulnerability: people who have had delirium are more likely to have it again with future illnesses, and it can sometimes unmask or worsen an underlying dementia. The findings from one episode help plan prevention next time — for example treating infections and constipation early and avoiding certain medicines.
Related tests, treatments or support
A delirium assessment is usually done alongside whatever investigations the suspected cause requires, such as tests for infection or a medication review. If dementia is suspected once the person recovers, a separate memory assessment may follow.
Follow-up & long-term care
The person should be reviewed as the cause is treated, with their confusion tracked day by day. If they were assessed at home or in a clinic, there should be a clear plan for who follows up and a number to call if things get worse. After recovery, a GP or memory service review can be arranged if concerns about thinking remain.
- Treat infections, constipation, pain and dehydration early in future, before they trigger another episode.
- Keep a current medicines list and question any new medicine that could affect the brain.
- Keep glasses and hearing aids working and worn.
- Maintain routine, daylight, activity and good sleep, which all reduce delirium risk.
Repeat, follow-on and what comes next
- Delirium often needs reassessment over hours and days because alertness fluctuates and the cause may declare itself late.
- More than one cause is common, so the plan may be revised as test results return.
- If confusion does not settle as expected, the diagnosis and the search for a cause should be revisited rather than assumed to be dementia.
- A separate, later assessment is often needed to answer the dementia question.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- A clearly identified, treated cause and a written plan the family understands.
- A named contact and number to call if the confusion returns or worsens.
- Sensible, time-limited use of any calming medicine, with a plan to stop it.
- Support to keep the person hydrated, mobile and oriented during recovery.
- A planned, later review of memory and thinking once the acute illness has resolved.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- Whether the assessment is urgent and where it takes place (home visit, clinic or hospital).
- Which tests are needed — bloods, urine, ECG, X-ray or a brain scan.
- The seniority of the clinician and how long the assessment takes.
- Whether a follow-up memory assessment is needed once the person recovers.
- Any treatment the cause requires, such as fluids or medicines.
- Reports or letters for the family, GP or other services.
- The clinician's assessment fee and how long the appointment is.
- Which tests are included and which are charged separately.
- Whether home visits are possible and at what cost.
- What happens — and what it costs — if the person needs to be admitted.
- Whether a written report and a follow-up review are included.
- What happens if the cause is not clear at first and further tests are needed.
On the NHS? Sudden confusion in an older person is assessed urgently on the NHS; private assessment may be used for speed, a second opinion or follow-up review of memory once the acute illness has settled.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Assuming an older person lacks capacity and not involving them in decisions they can still take part in.
- Not taking a collateral history, so the crucial 'this is sudden and new' is missed.
- Putting confusion down to dementia or 'old age' without looking for a treatable cause.
- Using sedating medicines without explaining that they can worsen delirium and cause falls.
- No clear plan or contact for the family if the person deteriorates.
Marketing red flags
- Any service offering to 'diagnose dementia' from a single visit while someone is acutely confused.
- A standalone cognitive test sold without assessment and treatment of the underlying illness.
- Reassurance that confusion is 'just age' without examination or tests.
- Routine brain scanning offered to everyone with confusion, regardless of clinical need.
Choosing a specialist safely
- Check the psychiatrist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the psychiatrist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good psychiatrist will welcome every one of these.
- What do you think is causing the confusion, and what is being done about it?
- Is this delirium, dementia, or both — and how will you tell?
- What tests are you doing, and what will the results change?
- What should we watch for at home, and who do we call if it gets worse?
- Are any of the current medicines making this worse?
- When and how will you check whether memory has recovered afterwards?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the psychiatrist who carries out my test, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this test not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Is delirium the same as dementia?
Is sudden confusion an emergency?
What usually causes delirium?
Will the confusion get better?
Can this be assessed at home?
How can I help my relative during delirium?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: Alzheimer's Society — Delirium NICE CG103 — Delirium: prevention, diagnosis and management NHS — Confusion SIGN 157 — Risk reduction and management of delirium Royal College of Psychiatrists — Delirium in older people
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
Related guides: Dementia diagnosis · Behavioural and psychological symptoms of dementia · Acute medical consultation · Alzheimer's disease assessment and treatment · Best-interests and care-planning assessment