Spironolactone (Aldactone) is a prescription medication that's used to diagnose and treat several different conditions, including high blood pressure. It may also help diagnose and treat a condition in which the body has too much aldosterone, which is a hormone that helps regulate the body's levels of water and salt. Spironolactone may also be used to treat swelling and fluid retention (edema) in people with cirrhosis, congestive heart failure, or nephrotic syndrome (a kidney disorder). Spironolactone is a type of medication called a potassium-sparing diuretic. It works by regulating the levels of salt and potassium in the body. Spironolactone comes as a tablet that is taken orally. Spironolactone is the generic name for the active ingredient in the brand-name medication Aldactone. Talk to your doctor to determine whether spironolactone is right for you.