A stroke happens when blood flow to part of the brain is interrupted, either by a clot blocking an artery or by bleeding into the brain. Brain tissue that loses its blood supply begins to be injured quickly, which is why stroke care is built around speed. The phrase clinicians use is simple: time is brain.
The FAST test
FAST is a way to remember the most common warning signs of a stroke. You do not need medical training to use it, and you do not need to be certain — recognizing the possibility is enough.
F — Face drooping
Does one side of the face droop, or feel numb? Ask the person to smile and look for an uneven smile.
A — Arm weakness
Is one arm weak or numb? Ask the person to raise both arms and watch for one arm drifting downward.
S — Speech difficulty
Is speech slurred or hard to understand? Is the person unable to speak, or struggling to find words?
T — Time to call 911
If you see any of these signs, even if they seem to go away, call 911 immediately. Note the time the symptoms started if you can — that single detail shapes which treatments are available.
Why you should call 911 rather than drive
It is natural to want to drive a family member to the hospital yourself, but calling 911 is usually the better choice. Paramedics can begin assessing the patient on the way, and they can route to a hospital equipped for stroke treatment rather than the nearest emergency room. Many hospitals also begin preparing for the patient's arrival while the ambulance is still en route, which saves time that would otherwise be spent in triage.
Symptoms that resolve still need evaluation
Sometimes stroke symptoms disappear within minutes. This can be a transient ischemic attack, sometimes called a TIA or a mini-stroke. A TIA is not harmless — it is a warning that a larger stroke may follow, sometimes within days. Anyone whose stroke symptoms resolve on their own should still be evaluated urgently.
Other symptoms worth knowing
FAST covers the most common presentations, but strokes can also cause sudden severe headache with no known cause, sudden trouble seeing in one or both eyes, sudden dizziness or loss of balance and coordination, or sudden confusion. The common thread is that the onset is sudden.
What happens next
At the hospital, imaging determines whether the stroke is caused by a clot or by bleeding, because the treatments differ. For clot-caused strokes, options may include clot-dissolving medication and, for larger vessel blockages, a catheter-based procedure to remove the clot. Which options apply depends on the imaging, the timing, and the individual patient.
This article is general health information, not medical advice, and does not replace evaluation by a clinician who knows your history. If you think you may be having a stroke or another neurological emergency, call 911.
