Diseases & care
Recognising a stroke: act FAST and why time is brain
A stroke is a brain attack — a sudden interruption to the brain's blood supply — and it is one of the few emergencies where a member of the public spotting it quickly can directly change the outcome. Modern treatments can limit or even reverse the damage, but only if given fast. This guide explains how to recognise a stroke and why speed matters so much.
Education and reference only. This article explains how treatments work in plain language — it contains no doses and is not a substitute for advice from your doctor or pharmacist. Always discuss your own treatment with a qualified clinician.
What a stroke is
A stroke happens when part of the brain is suddenly deprived of blood, and therefore oxygen. Brain cells begin to die within minutes. There are two main types. An ischaemic stroke — by far the most common — is caused by a clot blocking an artery to the brain. A haemorrhagic stroke is caused by a blood vessel bursting and bleeding into or around the brain. The two need different treatments, which is why urgent brain imaging is done before any clot-busting treatment.
The FAST test
The simplest way to recognise a stroke is the FAST test. Face: has the face drooped on one side; can the person smile evenly? Arms: can they raise both arms and keep them up, or does one drift down? Speech: is their speech slurred or garbled; can they understand you? Time: if you see any single one of these signs, it is time to call 999 immediately. Other sudden signs include numbness or weakness on one side, sudden confusion, severe headache, loss of vision, or trouble walking — but FAST captures the commonest and is easy to remember under pressure.
Why "time is brain"
In a stroke, an estimated 1.9 million neurons are lost every minute that treatment is delayed — hence the phrase "time is brain". The treatments that make the biggest difference are strictly time-limited. Thrombolysis (a clot-busting drug) can restore blood flow but only works within a few hours of symptom onset and only for ischaemic stroke. Thrombectomy — physically removing a large clot with a catheter — has widened the treatment window and can produce dramatic recovery, but again depends on speed and reaching a specialist centre. Every minute saved before treatment translates into brain preserved.
Treatment, recovery and prevention
After emergency treatment, stroke care continues on a specialist stroke unit, where early rehabilitation — physiotherapy, speech and language therapy, occupational therapy — helps the brain recover and relearn. Preventing another stroke is central: managing blood pressure, treating atrial fibrillation with anticoagulation, lowering cholesterol, stopping smoking and, where appropriate, antiplatelet medicines. A "mini-stroke" or TIA (transient ischaemic attack), where symptoms resolve within 24 hours, is a serious warning that needs urgent assessment because it can precede a major stroke.
In short
Key takeaways
- A stroke is a sudden loss of blood supply to part of the brain; brain cells die within minutes.
- Use FAST: Face drooping, Arm weakness, Speech difficulty, Time to call 999 — any one sign is enough to act.
- Treatments (clot-busting drugs and clot removal) are highly time-dependent — "time is brain".
- A TIA or "mini-stroke" resolves quickly but is a serious warning that needs urgent assessment.
- Preventing further strokes centres on blood pressure, atrial fibrillation, cholesterol and stopping smoking.
Answers
Frequently asked questions
What should I do if I think someone is having a stroke?
Call 999 immediately — do not wait to see if symptoms pass. Note the time symptoms started, as this affects which treatments can be given. A stroke is always a medical emergency.
What is a TIA or mini-stroke?
A transient ischaemic attack causes stroke-like symptoms that resolve, usually within minutes to hours. It is a serious warning sign of a possible future stroke and needs urgent medical assessment even after symptoms disappear.
Can a stroke be reversed?
Fast treatment — clot-busting drugs or mechanical clot removal for ischaemic stroke — can limit or sometimes reverse damage, but only within a limited time window, which is why acting immediately is critical.
Go deeper
Related guides
Sources
Where this is drawn from
- NICE NG128 — Stroke and transient ischaemic attack in over 16s
- Stroke Association — Act FAST
- Royal College of Physicians — National Clinical Guideline for Stroke
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