Hi, Captopril inhibitor of angiotensin I-converting enzyme (ACE), the enzyme responsible for the conversion of angiotensin I to angiotensin II. Captopril can be used for hypertention,heart failure,left ventricular dysfunction and diabetic nephropathy. side effects:signs of an allergic reaction severe stomach pain; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have a serious side effect such as: feeling light-headed, fainting; urinating more or less than usual, or not at all; fever, chills, body aches, flu symptoms; pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating; easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red... it can cause systemic side effects related to renal,cardiovascular,dermatology,heamatology. patients who are hypersensitive ti this drug should be avoided.