Sudden confusion (delirium)

Sudden confusion (delirium) can have many different causes. Get medical help immediately if someone suddenly becomes confused (delirious).

How to tell if someone is confused

If a person is confused, they may:

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.

Non-urgent advice: See a GP if:

  • you're worried that you or a relative are becoming increasingly 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.

Immediate action required: 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.

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.


  • 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


  • 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:

Page last reviewed: 14 June 2021
Next review due: 14 June 2024