What is Inderal (Propranolol)? This medication is a beta blocker used to treat high blood pressure, irregular heartbeats, shaking (tremors), and other conditions. It is used after a heart attack to improve the chance of survival. It is also used to prevent migraine headaches and chest pain (angina). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. Preventing chest pain can help improve your ability to exercise.