The acronym FAST can help. F: Face drooping. Can the person smile? Is the smile uneven? A: Arm weakness. Is one arm weak or numb? If the person raises both arms, does one drift down? S: Speech difficulty. Is the person's speech slurred? Can they repeat simple sentences you give them? T: Time to call 911. If the person shows any of these symptoms, even if the symptoms go away, call 911. Check the time so you know when the symptoms began.