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Face, Arms, Speech, Time. The NHS is explicit that stroke symptoms can pass on their own and you should still call 999 — including if the signs appeared within the last 24 hours and have gone.
There are only four things to check, and you can do them from across a room.
Face
Ask them to smile. One side of the face may droop — the mouth or eye pulling downward, the smile arriving lopsided.
Arms
Ask them to raise both arms and hold them up. They may not be able to fully lift both, or one may drift back down while the other stays.
Speech
Ask them a simple question. They may slur their words or sound confused — reaching for a word that will not come, or answering something you did not ask.
Time
Call 999.
The part people get wrong
Stroke symptoms can stop on their own. The face lifts, the speech comes back, the arm works again, and everybody in the room relaxes.
The NHS wording is unambiguous: "Symptoms of a stroke can sometimes stop after a short time, so you may think you're OK. Even if this happens, get medical help straight away."
And it extends the window well past the moment: call 999 if there have been signs of a stroke within the last 24 hours, even if they have now stopped.
Symptoms that resolve can indicate a transient ischaemic attack — often called a mini-stroke. It is not a lesser event to be relieved about. It is a warning that carries a substantial risk of a full stroke in the days that follow, and it is treatable if someone knows about it.
Other signs worth knowing
FAST covers the most common presentation, not every one. The NHS also lists weakness down one side of the body, vision problems, difficulty speaking, confusion, dizziness, a severe headache, and nausea or vomiting.
A sudden severe headache with no obvious cause, in someone who does not get them, is worth taking seriously on its own.
Why the clock is the whole thing
Stroke treatment is time-limited in a way most emergencies are not. The interventions that break up or physically remove a clot only work within a window from when symptoms started.
Which is why the first question in the ambulance and in the hospital is always the same: when did it start?
If you find someone already affected and do not know, the time they were last seen well is the number that matters. Note it. It will be asked.
- What does FAST stand for?
- Face — one side of the face may droop. Arms — the person may not be able to fully lift both arms. Speech — they may slur their words or sound confused. Time — call 999.
- Should you call an ambulance if stroke symptoms stop?
- Yes. The NHS says symptoms can sometimes stop after a short time, so you may think you are OK, and that you should get medical help straight away even if that happens. It says to call 999 if there have been signs of a stroke within the last 24 hours, even if they have now stopped.
- What other symptoms can a stroke cause?
- The NHS also lists weakness down one side of the body, vision problems, difficulty speaking, confusion, dizziness, a severe headache, and nausea or vomiting.
- Why does speed matter so much with stroke?
- Because the treatments that break up or remove a clot only work inside a limited window after symptoms begin. Arriving late does not just delay treatment, it can remove the option entirely.
Every figure above comes from the sources below, as they reported it, on the date given.
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Facts verified against these sources on 20 August 2026
