Propranolol is a type of medicine called a beta blocker. Like other beta blockers, propranolol works by changing the way your body responds to some nerve impulses, including in the heart.

Can propranolol damage your heart?

Propranolol may cause heart failure in some patients. Check with your doctor right away if you are having chest pain or discomfort, dilated neck veins, extreme fatigue, irregular breathing, an irregular heartbeat, swelling of the face, fingers, feet, or lower legs, or weight gain.

When should you not take propranolol?

You should not use propranolol if you have asthma, very slow heart beats, or a serious heart condition such as "sick sinus syndrome" or "AV block" (unless you have a pacemaker). Babies who weigh less than 4.5 pounds should not be given Hemangeol oral liquid.