How does tPA help people having a stroke?

tPA has been shown to be effective in treating ischemic (is-KEM'ik) stroke. This kind of stroke is usually caused by blood clots that block blood flow to the brain.

In 1996 the U.S. Food and Drug Administration (FDA) approved the use of tPA to treat stroke in the first three hours following the onset of symptoms. This makes it very important for people who think they're having a stroke to seek help immediately. If given promptly, tPA can significantly reduce the effects of stroke and reduce permanent disability.