Delirium (acute confusion) assessment
An urgent assessment when someone becomes suddenly confused, to confirm delirium, find and treat the cause, and protect the person — because delirium is a medical emergency that is often reversible.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- Sudden new confusion is a medical emergency and needs urgent assessment, not a routine appointment.
- Delirium is often reversible — it is usually caused by something treatable such as infection, pain, constipation, dehydration or a medicine.
- Finding and treating the underlying cause is the main goal, alongside keeping the person safe and oriented.
- Delirium is not the same as dementia, though the two can occur together and be confused with each other.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Recognises delirium, which is otherwise easily missed, especially the quiet (hypoactive) form.
An elective private appointment is the wrong route for someone who is acutely confused now — that needs urgent or emergency care.
Delirium is recognised, the search for the cause begins, observations and urgent tests are done, and the person is kept safe and calm.
Confirmation that the cause has been fully treated and confusion is resolving.
Delirium is recognised, the search for the cause begins, observations and urgent tests are done, and the person is...
The cause is treated (for example an infection or constipation). Confusion often begins to lift as the trigger...
Most people gradually return towards their usual selves. Sleep, hydration, mobility and orientation are supported...
Follow-up checks how well thinking has recovered, reviews medicines, and considers whether any underlying memory...
What is a delirium (acute confusion) assessment?
Delirium is a sudden change in someone's mental state — new confusion, disorientation, trouble paying attention, or a change in alertness — that comes on over hours or days and tends to come and go through the day. It is common in older people, especially when they are unwell or in hospital.
Sudden confusion should be treated as a medical emergency. The important and hopeful point is that delirium is often reversible: it is usually triggered by something treatable, such as an infection (for example a urine or chest infection), pain, constipation, dehydration, a medicine, or alcohol withdrawal. Finding and treating that cause is the heart of the assessment.
The assessment confirms whether this is delirium (using a quick bedside test such as the 4AT or the Confusion Assessment Method), then systematically searches for the cause with examination, observations, urine and blood tests, and a medicines review. It also keeps the person safe and comfortable.
Delirium is not the same as dementia, though it can be mistaken for it and can happen in people who already have dementia. Recognising delirium matters because the cause can often be put right and the confusion can clear.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Options at a glance
These are the main approaches described in this guide. The right option depends on the diagnosis, your goals and what your clinician thinks is safe.
Recognising delirium (screening)
A quick bedside test such as the 4AT or the Confusion Assessment Method (CAM) checks for sudden onset, fluctuating course, inattention and disorganised thinking. It takes...
Hyperactive delirium
The person is restless, agitated or distressed, may pace, and can have hallucinations or false beliefs. This form is easier to notice but can be frightening for everyone.
Hypoactive delirium
The person becomes quiet, drowsy, withdrawn and slow. This is the most common form and is easily missed or mistaken for tiredness or low mood.
Finding the cause
A systematic search for triggers: infection, pain, constipation, urinary retention, dehydration, medicines, alcohol withdrawal, low oxygen, and other illnesses. Often more...
Preparing for your test
- If someone becomes suddenly confused, do not wait for a routine appointment — seek urgent medical help the same day, and call 999 if they are very unwell.
- Bring or tell the team a clear account of how quickly the confusion started and how it changes through the day.
- Bring a full, up-to-date list of all medicines, including recently started, stopped or over-the-counter ones.
- Tell the team about alcohol use, as withdrawal can cause delirium.
- Describe the person's usual mental state, so new changes can be told apart from long-standing memory problems.
- Mention recent illness, falls, pain, constipation, poor fluid intake or a urinary catheter.
- Bring glasses and hearing aids — being able to see and hear helps a confused person enormously.
What happens
A clinician first confirms whether this is delirium using a quick bedside test such as the 4AT, comparing the person's current state with how they usually are. Information from family or carers about the speed of change is essential.
The team then searches for the cause. They examine the person, check observations such as temperature, oxygen, pulse and blood pressure, test the urine and blood, review all medicines, and look for pain, constipation or a full bladder. A chest X-ray or, in selected cases, a brain scan may be done depending on the findings. Often more than one cause is present.
Treatment is aimed at the cause — for example treating an infection, relieving constipation or pain, correcting dehydration, or stopping a culprit medicine. Alongside this, the person is kept safe, calm and oriented: a quiet environment, familiar faces, glasses and hearing aids, good sleep, hydration and gentle reassurance. Sedating medicines are avoided where possible and used only carefully when essential.
Family and carers are important partners throughout, both in giving history and in helping the person feel safe.
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…
- An elective private appointment is the wrong route for someone who is acutely confused now — that needs urgent or emergency care.
- It is the wrong pathway if the person needs emergency treatment for sepsis, stroke or another acute illness.
- It is not a memory clinic; long-standing, slowly progressive memory problems need a separate dementia assessment.
- Reassurance alone is unsafe — sudden confusion must trigger a search for a cause, not watchful waiting.
Delay or rearrange if…
- Never delay urgent assessment of new confusion — the priority is to act, not to wait.
- A formal memory (dementia) assessment should usually wait until the delirium has resolved, as confusion distorts the results.
- Non-urgent follow-up can wait until the acute illness is treated and the person is stable.
- If the person is rapidly deteriorating, call 999 rather than arranging any appointment.
Alternatives to discuss
- Urgent NHS assessment in hospital or the community is the standard and safest route for acute confusion.
- Treating the specific cause (for example an infection) directly.
- A comprehensive geriatric assessment for frail older people with recurring problems.
- A later, separate memory assessment if cognition does not fully recover.
- Supportive, non-drug measures (orientation, hydration, sleep) as core management.
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
- Recognises delirium, which is otherwise easily missed, especially the quiet (hypoactive) form.
- Finds and treats reversible causes, so the confusion can often clear.
- Reduces the risk of harm, such as falls and dehydration, during the confused period.
- Distinguishes delirium from dementia, guiding the right care and follow-up.
- Supports family and carers with explanation and a plan.
Risks & complications
- Distress and fear for the person and their family during the confused period.
- Discomfort from blood tests, a urine sample or other investigations.
- Disturbed sleep and disorientation, especially in an unfamiliar hospital setting.
- Needing several tests before the cause becomes clear.
- More than one cause, so treatment and recovery take longer.
- Side effects from any medicine used to manage severe agitation.
- Incidental findings on scans that need further checks.
- A prolonged recovery, with confusion taking weeks to fully settle in some people.
- A serious underlying illness (such as severe infection or a stroke) found as the cause, needing urgent treatment.
- Delirium not fully resolving, particularly in people with existing dementia.
- Harm from sedating medicines if used without care, which is why they are minimised.
The biggest risk is failing to recognise delirium, especially the quiet form, and missing a serious treatable cause behind it. Sedating medicines can worsen confusion, falls and other harms, so they should be a last resort and used at the lowest effective dose for the shortest time. Always ask the team what they think the cause is and how it is being treated.
Published figures to discuss
How often delirium occurs, and how fully people recover, varies greatly with age, frailty, the cause, and whether someone already has dementia. It is common in unwell older people, especially in hospital, and the quiet form is often missed. Because recovery and recurrence depend so much on the individual and the cause, exact percentages are not quoted here; the team can explain the likely course for the person in front of them.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Delirium in older acute hospital patients | Common; often reported in about 20 to 30% of older medical inpatients | Rates are higher with dementia, severe illness, surgery and intensive care. | NICE CG103 — Delirium: prevention, diagnosis and management (recommendations)nice.org.ukPublished figure |
| Delirium in ventilated ICU patients | Very common; intensive-care guidance quotes rates up to around 74% | This is why regular delirium screening and lighter sedation where possible matter. | NICE CG103 — Delirium: prevention, diagnosis and management (recommendations)nice.org.ukPublished figure |
| Delirium being missed or mistaken for dementia | Common | Acute change, fluctuation and inattention are the clues; collateral history from family or carers is often decisive. | Guide sourcesClinical context |
| Longer-term decline after delirium | Clinically important; delirium is linked with longer stay, institutionalisation and mortality | Delirium should trigger investigation of causes and prevention of recurrence, not just sedation. | NICE CG103 — Delirium: prevention, diagnosis and management (recommendations)nice.org.ukSource-linked 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
Recovery here means recovery from the delirium itself. Once the cause is treated, many people improve over days, though for some, particularly those with dementia, it can take weeks to settle fully, and not everyone returns completely to their previous state.
- Confusion that comes and goes through the day before it settles.
- Tiredness, low mood or poor sleep for a while afterwards.
- Patchy memory of the confused period, which is common and not harmful.
- Gradual rather than instant return to normal, especially in frail or older people.
Aftercare
- Make sure the treated cause (such as an infection or constipation) is fully resolved.
- Keep the person hydrated, eating, moving and sleeping well, with day-night routine restored.
- Ensure glasses, hearing aids and familiar surroundings or faces are available.
- Review medicines, especially any that were started or that may have contributed.
- Watch for confusion returning, which can signal a new or recurring cause.
- Arrange follow-up to check recovery and to assess memory later if needed.
- Support family and carers, who may find the episode distressing.
- Clear account of how and when the confusion started
- Full, current medicine list including recent changes
- Information about alcohol use
- Description of the person's usual mental state
- Glasses and hearing aids available
- Notes on recent illness, pain, constipation or fluid intake
- A trusted family member or carer to give history and support
⚠ Get urgent help if…
- Sudden new confusion in an older person — seek urgent medical help the same day.
- Confusion with fever, breathlessness, chest pain or a fast heartbeat — call 999.
- Facial droop, arm weakness or slurred speech — possible stroke, call 999.
- Becoming very drowsy, hard to wake, or unresponsive.
- Severe agitation putting the person or others at risk of harm.
- Not passing urine, severe pain, or signs of a serious infection.
- Confusion returning after it had cleared, which needs prompt reassessment.
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 specialist gives you.
Results & realistic expectations
A good assessment recognises the delirium, identifies one or more treatable causes, and treats them, so that for many people the confusion clears over days. It also keeps the person safe and tells delirium apart from dementia.
Recovery is not always quick or complete. In frail or older people, and especially those with existing dementia, confusion can take weeks to settle, and some do not return fully to their previous level. Having had delirium can also be a sign of underlying vulnerability, so follow-up and, where appropriate, later memory assessment are important.
Delirium is usually a short-term, reversible problem once the cause is treated, but it can recur if the person becomes unwell again, and it can unmask or worsen an underlying memory problem. Because of this, the focus afterwards is on preventing future episodes (treating illness early, reviewing medicines, staying hydrated and active) and on reassessing thinking over time if concerns remain.
Related tests, treatments or support
Delirium assessment usually happens alongside treating the underlying illness and a full medicines review. In older people it often forms part of a comprehensive geriatric assessment, and may be combined with falls prevention, nutrition and hydration support, and later memory (dementia) assessment if cognition does not fully recover.
Follow-up & long-term care
After recovery, follow-up should check how well thinking has returned to normal, confirm the cause was fully treated, and review medicines. If memory or thinking problems persist, a later, separate memory assessment may be arranged. Family and carers should be told what happened, what to watch for, and who to contact if confusion returns.
- Treating new illnesses promptly to reduce the chance of further delirium.
- Ongoing medicines review to avoid drugs that can trigger confusion.
- Maintaining hydration, nutrition, activity and good sleep routines.
- Ensuring glasses and hearing aids are used and working.
- Arranging a later memory assessment if thinking does not fully recover.
Repeat, follow-on and what comes next
- The cause is often revised or added to, as more than one trigger is frequently present.
- Recovery may take longer than expected, and confusion can fluctuate before it settles.
- If thinking does not return to normal, a later dementia assessment may be needed.
- Delirium can recur with further illness, prompting reassessment each time.
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
- Confirmation that the cause has been fully treated and confusion is resolving.
- Support for orientation, sleep, hydration, nutrition and mobility during recovery.
- A clear medicines review and a named contact for questions.
- Explicit advice to family on what to watch for and when to seek urgent help.
- A plan for later memory assessment if thinking does not fully recover.
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:
- This is acute care; in the NHS it is handled urgently and not on a private elective basis.
- If seen privately for follow-up, the specialist's assessment time.
- Investigations to find or confirm the cause (urine and blood tests, imaging).
- Any treatment of the underlying cause.
- Follow-up review of recovery and medicines.
- Any later memory assessment if thinking does not fully recover.
- Confirmation that acute confusion should be handled urgently, not as an elective booking.
- For any private follow-up, the specialist's assessment fee.
- Investigation fees and who reports them.
- Follow-up appointments to review recovery.
- What happens, and what it costs, if urgent hospital transfer is needed.
- Any later memory assessment and its cost.
On the NHS? Delirium is an acute medical problem assessed and treated urgently by the NHS in hospital and the community; it is not a routine private booking, though private geriatric services may help with follow-up once the acute episode is over.
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
- Treating acute confusion as routine rather than as an emergency needing a cause to be found.
- Mistaking delirium for dementia and missing a reversible cause.
- Using sedating medicines as a first resort rather than treating the cause.
- Not involving family or carers, who hold key history and provide reassurance.
- Assessing capacity and consent without accounting for the fluctuating confusion.
Marketing red flags
- Offering an elective private 'confusion clinic' slot for someone acutely confused instead of urgent care.
- Promising to reverse confusion without identifying and treating the cause.
- Selling brain scans as the answer when most causes are found from history, examination and simple tests.
- Reaching for sedation as the main treatment for agitation.
- Conflating delirium with dementia for the sake of a packaged 'memory' service.
Choosing a specialist safely
- Check the specialist 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 specialist 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 specialist will welcome every one of these.
- Do you think this is delirium, and what do you think has caused it?
- What tests are being done to find the cause, and what have they shown?
- How is the cause being treated, and how long might recovery take?
- Could any medicines be contributing, and can they be changed?
- How can we keep them safe and oriented, and avoid sedatives if possible?
- What should we watch for afterwards, and should memory be assessed later?
- 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 specialist 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 sudden confusion an emergency?
Is delirium the same as dementia?
What usually causes delirium?
Can delirium be cured?
How can I help someone who is delirious?
Are sedatives used?
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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: British Geriatrics Society — Delirium NICE CG103 — Delirium: prevention, diagnosis and management (recommendations) British Geriatrics Society — CGA: confusion and delirium NICE CG103 — Rationale and impact NHS (Ashford and St Peter's) — Delirium information
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.
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