Captopril (Capoten®) belongs to a class of medicines known as angiotensin converting enzyme (ACE) inhibitors. It is used to treat mild to severe high blood pressure as well as congestive heart failure. It is also sometimes prescribed for other uses; ask your doctor for more information. Captopril is given as a tablet, usually two to three times daily, on an empty stomach. A liquid suspension is also available. Your doctor may start with a low dose, and gradually increase as needed.