The FAST stroke test is a simple memory aid that helps you recognize the most common signs of a stroke in yourself or someone else. FAST stands for Face, Arm, Speech, and Time. It takes less than a minute to perform, requires no medical training, and correctly identifies strokes about 87.5% of the time when used by non-medical people.
What Each Letter Means
F is for Face. Ask the person to smile. During a stroke, one side of the face often droops or doesn’t move the way the other side does. The smile will look uneven, or one corner of the mouth will sag downward. This happens because a stroke disrupts the brain’s ability to control muscles on one side of the body.
A is for Arm. Ask the person to raise both arms out in front of them and hold them there. If one arm drifts downward or can’t be raised at all, that’s a warning sign. Sudden weakness or numbness on one side of the body is one of the hallmark symptoms of stroke.
S is for Speech. Ask the person to repeat a simple sentence, like “The sky is blue.” Listen for slurring, garbled words, or an inability to speak at all. Some people can still talk but can’t understand what you’re saying to them, which also counts as a positive sign.
T is for Time. If any of the first three signs are present, call emergency services immediately. The “T” exists to reinforce that stroke treatment is extremely time-sensitive, and waiting to see if symptoms improve can cost someone their recovery.
Why Minutes Matter
Stroke treatment works by restoring blood flow to the brain, and every minute of delay means more brain tissue is lost. The primary clot-dissolving treatment for the most common type of stroke (ischemic stroke) must be given within a limited window after symptoms start, and its effectiveness drops rapidly with each passing minute.
Patients who receive treatment within 60 minutes of symptom onset have 35% higher odds of a good outcome at three months compared to those treated after the first hour. For every 30-minute delay beyond that, the chances of a favorable recovery continue to decline. This is why neurologists refer to the first hour as the “golden hour” for stroke treatment.
When paramedics identify a likely stroke using FAST before arriving at the hospital, the emergency department can prepare in advance. Studies show that pre-hospital stroke notification cuts the time from hospital arrival to brain scan from 18 minutes down to 12, and the time from arrival to treatment from 24 minutes to 20. Those few minutes translate directly into better outcomes.
How Accurate FAST Really Is
FAST picks up roughly 87.5% of strokes, which makes it a reliable screening tool for people with no medical background. That said, it does miss some strokes. The symptoms it checks for, particularly facial drooping, arm weakness, and speech problems, correspond to strokes affecting the front part of the brain. Strokes in other areas can cause different symptoms that FAST doesn’t cover.
The test also has a relatively high false-positive rate, meaning it sometimes flags conditions that aren’t strokes (like severe migraines or seizures) as potential strokes. That’s by design. In an emergency, it’s far better to call for help and have it turn out to be something else than to miss an actual stroke.
BE FAST: The Expanded Version
Some health systems now promote an updated version called BE FAST, which adds two additional warning signs before the original four. The Cleveland Clinic and other major centers have adopted this version because it catches strokes that the original FAST can miss.
- B is for Balance: sudden loss of balance or coordination, difficulty walking, or unexplained dizziness.
- E is for Eyes: sudden vision changes, including loss of sight in one or both eyes or new double vision.
- F is for Face: drooping or uneven facial features.
- A is for Arms (and legs): sudden weakness in a limb on one side of the body.
- S is for Speech: slurred speech or trouble understanding others.
- T is for Time: call 911 immediately.
Balance problems and vision changes are common in strokes affecting the back of the brain, which the original FAST tends to miss. If you can only remember one version, either works. The core principle is the same: spot sudden, one-sided neurological symptoms and act fast.
What to Do if You Spot the Signs
Call emergency services rather than driving to the hospital yourself. Paramedics can begin assessment on the way and alert the hospital’s stroke team so everything is ready when you arrive. Note the exact time symptoms started, or the last time the person seemed normal. This detail directly affects which treatments are available.
Don’t give the person food, water, or medication while waiting for help. Strokes can impair swallowing, creating a choking risk. Keep them comfortable, ideally lying down with their head slightly elevated, and stay with them until paramedics arrive.