Clopidogrel is used alone or with aspirin to prevent serious or life-threatening problems with the heart and blood vessels in people who have had a stroke, heart attack, or severe chest pain. This includes people who have percutaneous coronary intervention (PCI; angioplasty; a type of heart surgery) that may involve inserting coronary stents (metal tubes surgically placed in clogged blood vessels to improve blood flow) or who have coronary artery bypass grafting (CABG; a type of heart surgery). Clopidogrel is also used to prevent serious or life-threatening problems with the heart and blood vessels in people who have peripheral arterial disease (poor circulation in the blood vessels that supply blood to the legs). Clopidogrel is in a class of medications called antiplatelet medications. It works by preventing platelets (a type of blood cell) from collecting and forming clots that may cause a heart attack or stroke.