Spironolactone is used to treat high blood pressure and heart failure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. It is also used to treat swelling (edema) caused by certain conditions (such as heart failure, liver disease) by removing excess fluid and improving symptoms such as breathing problems. This medication is also used to treat conditions in which the body is making too much of a natural substance (aldosterone). Spironolactone is known as a "water pill" (potassium-sparing diuretic).