Nifedipine belongs to a group of drugs that are termed "calcium channel blocking" agents. These drugs affect the movement of calcium into heart and blood vessel cells, and cause a relaxing effect of the muscles to allow an increased amount of blood flow into the heart. Many of these calcium channel blocking agents are used to treat angina pectoris (chest pain), and they are also used to help reduce blood pressure (antihypertensives). Side effects include breathing difficulty, coughing, irregular heartbeat, and swelling of the hands and feet.