Propranolol is a beta-blocker. Beta-blockers affect the heart and circulation (blood flow through arteries and veins). Propranolol is used to treat tremors, angina (chest pain), hypertension (high blood pressure), heart rhythm disorders, and other heart or circulatory conditions. It is also used to treat or prevent heart attack, and to reduce the severity and frequency of migraine headaches. Propranolol may also be used for purposes not listed in this medication guide.