How do I tell if someone is having a stroke?
The FAST test, the other symptoms it does not cover, why a stroke being painless is what makes people wait, and why symptoms that have stopped still need 999.
- Difficulty
- beginner
- Time
- 7 min
- Read
- 5 min
- Safety
- warning
Short answer
Face: ask them to smile — has one side dropped? Arms: ask them to raise both and hold them — can they, and does one drift down? Speech: is it slurred, or are they struggling for words or confused? Time: any one of those means ring 999 now and say you think it is a stroke. Signs within the last 24 hours that have since stopped also mean 999.
The FAST test is the most successful piece of public first aid teaching in Britain, and the reason it works is that it removes the need to be sure. You are not diagnosing anything. You are checking three things and, if any one of them is wrong, making a phone call.
Safety
Step by step
- Face — ask them to smile.Look for one side of the face drooping. The eye or the mouth on one side may have fallen. It can be subtle, and comparing the two sides is what makes it visible.
- Arms — ask them to raise both and keep them up.Can they lift both arms at all, and if they can, does one drift downwards while they are trying to hold it? Weakness on one side is the pattern.
- Speech — ask them a simple question.Slurred words, sounding confused, or being unable to find ordinary words. Someone who knows them will notice this fastest.
- Time — ring 999 on any one of them.Say you think it is a stroke. That phrase changes the response, because stroke treatment is time-critical and the ambulance service routes it differently.
- Know the symptoms FAST does not include.The NHS also lists weakness or numbness down one side of the body, blurred vision or loss of sight in one or both eyes, difficulty speaking or thinking of words, confusion, dizziness, a sudden severe headache, and feeling or being sick. Any of these warrants the same call.
- Understand why people wait.A stroke is usually painless. There is no chest pain, no obvious injury, and the person themselves may be confused about what is happening, which is exactly why the people around them have to make the decision.
- Ring 999 even if the symptoms have stopped.NHS advice is to ring 999 if there have been signs of a stroke within the last 24 hours even if they have now resolved. Symptoms that come and go can be a warning of a larger stroke to follow, and that warning is a reason to act, not a reason to relax.
- Note the time symptoms started.This is the single most useful piece of information you can give. Treatment options depend on how long ago it began, so the last time the person was definitely normal matters enormously.
- Stay with them and keep them comfortable.Nothing to eat or drink, because swallowing may be affected. If they become unresponsive, check breathing: breathing normally means the recovery position, not breathing normally means CPR.
Tips
- "I think this is a stroke" is the sentence to use on the phone. It is not overclaiming — it is describing what you have observed and it triggers the right response.
- If you are unsure whether the face is drooping, ask them to show their teeth. It exaggerates the asymmetry and is easier to read than a smile.
- Anyone can do the FAST test on themselves in a mirror if they suspect something is wrong, and that is a legitimate use of it.
Common mistakes
- Waiting to see whether it passes — Stroke treatment is time-limited and the tissue at risk is being lost while you wait. Symptoms improving is not evidence that treatment is unnecessary.
- Driving them to hospital yourself — The ambulance service can begin assessment on the way and takes the person to the right hospital for stroke treatment, which is not always the nearest one.
- Giving them a drink to see if they are all right — Swallowing is often affected in a stroke, and giving fluid to someone who cannot swallow safely risks it going into the lungs.
- Assuming it cannot be a stroke because the person is young — Strokes are more common with age and they are not confined to older people. The signs are what matter, not the age of the person showing them.
If it doesn't work
One arm is weak but speech and face seem normal
Cause: A stroke can present with any one of the signs alone — Fix: Ring 999. The test is designed so that one positive sign is enough, precisely so nobody has to judge which combination counts.
Symptoms lasted a few minutes and resolved completely
Cause: This may have been a transient ischaemic attack — Fix: NHS advice is to ring 999 for stroke signs within the last 24 hours even if they have stopped. Complete resolution is not reassurance; it is a warning.
They are refusing to let you call
Cause: Confusion is itself a stroke symptom, and people often minimise — Fix: Ring anyway and explain the situation to the handler. Someone whose judgement may be affected by the event is not in a position to decline assessment of it.
Questions people ask
What does FAST stand for?
Face, Arms, Speech, Time to call 999. The first three are the checks and the fourth is the instruction.
Is a mini-stroke serious?
Yes. Symptoms that resolve are treated as a warning that requires urgent assessment, and NHS advice is to ring 999 for stroke signs in the last 24 hours even if they have stopped.
Can a stroke look like being drunk?
It can — slurred speech, unsteadiness and confusion together. That is a recognised and dangerous misreading, particularly in public, and it is why the FAST checks are worth doing rather than assuming.
What happens after the 999 call?
Stroke is treated as a time-critical emergency. Being able to say when the person was last definitely normal is the information that shapes what happens next, so work it out while you wait.