Sudden confusion (delirium)

NHS Choices information on acute (sudden) confusion, with links to other useful resources.

What to do if someone is showing signs of confusion

While you wait for the ambulance

Common causes of sudden confusion

More unusual causes of sudden confusion



A simple test for confusion is to ask the person their name, age and today's date, and see if they seem unsure or answer incorrectly.

It's understandable to fear the worst and assume it's a sign of dementia – but if the confusion came on over a short period of time (acute confusion), dementia is unlikely to be the sole cause.

## What to do if someone is showing signs of confusion

If the confusion has come on suddenly, take them to your nearest hospital or for an ambulance, especially if they're showing other signs of illness such as a fever, or their [skin or lips are turning blue](/health-library/symptoms/cyanosis) .

If the person is diabetic...

If the person is diabetic, check their blood sugar level. You can check this if they have a testing device with them. You'll need to prick their finger with the device and place the droplet of blood on the testing strip. Compare the reading with these target blood sugar levels.

- If the reading is high, take them to hospital or call an ambulance.
- If the reading is low, give them a sugary snack or drink. Wait 10 minutes to see if they recover. If they don't, take them to hospital or call an ambulance.

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## While you wait for the ambulance

- Stay with them  . Introduce yourself if you need to, reassure them, and remind them where they are at regular intervals.
- Check the person's medication cupboard  – if in their home – and make a note of what drugs they're taking.
- Ask if any other family members have been unwell, to check whether [carbon monoxide poisoning](/health-library/conditions/carbon-monoxide-poisoning) could be a possible cause of the confusion.



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## Common causes of sudden confusion

The most common causes of sudden confusion are:

- a lack of oxygen in the blood (hypoxia)  – the cause could be anything from a severe asthma attack to a problem with the lungs or heart
- an infection  anywhere in the body, especially in elderly people
- a  [stroke](/health-library/conditions/stroke)  or  [TIA](/health-library/conditions/transient-ischaemic-attack)  ("mini stroke")
- a [low blood sugar level](/health-library/symptoms/hypoglycaemia) (hypoglycaemia)
- [diabetic ketoacidosis](/health-library/conditions/diabetic-ketoacidosis/#symptoms)  , a serious complication of diabetes caused by a lack of insulin in the body
- certain medications  , including digoxin, diuretics, steroids, and opiates
- [alcohol poisoning](/health-library/conditions/alcohol-poisoning) or alcohol withdrawal
- drug misuse

This information should give you a better idea of the cause of someone's confusion, but shouldn't be used as a diagnostic tool. Always see your doctor for a proper diagnosis.

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## More unusual causes of sudden confusion

Less common causes of sudden confusion are:

- an infection of the brain or its lining (encephalitis or meningitis)
- an imbalance of salts and minerals in the blood
- a severely [underactive thyroid](/health-library/conditions/thyroid-under-active/#complications)  gland
- thiamine (vitamin B1) deficiency
- a brain tumour
- [hypoparathyroidism or hyperparathyroidism](/health-library/conditions/hypoparathyroidism-hyperparathyroidism) (rare hormone disorders)
- Cushing's disease (a tumour of the pituitary gland)
- an epileptic seizure
- [carbon monoxide poisoning](/health-library/conditions/carbon-monoxide-poisoning)

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References

All of Healthily's articles undergo medical safety checks to verify that the information is medically safe. View more details in our <a href="/safety" target="_blank" rel="noopener noreferrer">safety page</a>, or read our <a href="/legal/editorial-policy-principles" target="_blank" rel="noopener noreferrer">editorial policy</a>.

Article information

Being in a state of confusion means not being able to think clearly or quickly, feeling disorientated, and struggling to pay attention, make decisions, or remember things.