The most common adverse reactions to captopril are irritant dry cough and angioneurotic edema. Other adverse reactions include chest pain, upper respiratory symptoms, elevated blood creatinine and urea nitrogen, and taste disturbances. Severe hypotension may also occur on first treatment in patients already on high-dose diuretics with hyponatremia, dehydration, hypovolemia, and severe heart failure. Avoid captopril during pregnancy because it may cause abnormal fetal development and may even cause fetal death. In patients with moderate or greater renal insufficiency, especially with oliguria or anuria, the use of captopril may also cause hyperkalemia.