Sudden facial drooping, weakness in one arm, and slurred speech — call 120 immediately; don’t wait or drive yourself.

No cost at all. These three steps are easy to remember: ask the person to smile, raise both arms straight out, and say a complete sentence.

This conclusion comes from a meta-analysis of 16 randomized trials involving 6,756 patients. Intravenous thrombolysis means delivering medication to reopen blocked blood vessels. When alteplase is given within 3 hours of symptom onset, the odds of the patient regaining basic independence — defined as a modified Rankin score of 0–1 — increase by a factor of 1.75. The 95% confidence interval for this effect is 1.35–2.27. In other words, the likelihood of a good recovery is roughly 1.75 times higher with treatment. Waiting 3 to 4.5 hours lowers this advantage to 1.26 (95% CI 1.05–1.51), while after 4.5 hours the difference becomes statistically insignificant at 1.15 (95% CI 0.95–1.40).

Emberson J, Lees KR, Lyden P, et al. (2014). Effect of treatment delay, age, and stroke severity on the effects of intravenous thrombolysis with alteplase for acute ischaemic stroke: a meta-analysis of individual patient data from randomised trials. Lancet, 384(9958), 1929-1935. https://doi.org/10.1016/S0140-6736(14)60584-5

Thrombolysis involves administering medication to clear blocked blood vessels; the earlier it is given, the greater its effectiveness. After 4.5 hours, it provides little to no benefit. Calling 120 instead of driving is essential because ambulances transport patients directly to stroke centers where staff can be alerted in advance. Recording the exact time symptoms began helps doctors determine whether thrombolysis is still appropriate. Never give water or medicine, and never wait “to see if things get better on their own.”