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Symptom guide

Sudden confusion (delirium)

NHS information about sudden confusion (delirium), including how to tell if someone is confused and when to get medical help.

About this information

This NHS content is written for people in England. Services, contact routes and treatment arrangements may differ in other countries.

How to tell if someone is confused

If a person is confused, they may:

  • not be able to think or speak clearly or quickly
  • not know where they are (feel disorientated)
  • struggle to pay attention or remember things
  • see or hear things that are not there (hallucinations)

Try asking the person their name, their age and today's date. If they seem unsure or cannot answer you, they probably need medical help.

See a GP if:

  • you're worried that you or a relative have gradually become more forgetful or confused

It may not be anything serious, but it's best to get checked.

In older people, forgetfulness and confusion are sometimes signs of dementia.

Go to A&E or call 999 if:

  • someone suddenly becomes confused

Many causes of sudden confusion need to be assessed and treated as soon as possible. Sometimes it may be life threatening.

A&E safety messaging

Do not drive to A&E. Ask someone to drive you or call 999 and ask for an ambulance.

Bring any medicines you take with you.

Things you can do while waiting for an ambulance

If you're with someone who has suddenly become confused, there are things you can do while waiting for medical help.

Do

  • stay with the person – tell them who you are and where they are, and keep reassuring them

  • use simple words and short sentences

  • make a note of any medicines they're taking, if possible

Don't

  • do not ask lots of questions while they're feeling confused

  • do not stop the person moving around, unless they're in danger

Causes of sudden confusion

Sudden confusion can be caused by many different things. Do not try to self-diagnose. Get medical help if someone suddenly becomes confused or delirious.

Some of the most common causes of sudden confusion include:

Sudden confusion (delirium)

Symptoms

Sudden confusion (delirium)

Self-care

Sudden confusion (delirium)

Causes

Content supplied by the NHS website

Content supplied by the NHS website, refreshed 19 August 2026. View the original NHS article ↗

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