This drug is used to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. This medication is a combination of two "water pills" (diuretics): triamterene and hydrochlorothiazide. This combination is used by people who have developed or are at risk for having low potassium levels on hydrochlorothiazide. It causes you to make more urine, which helps your body get rid of extra salt and water. This medication also reduces extra fluid in the body (edema) caused by conditions such as heart failure, liver disease, or kidney disease. This can lessen symptoms such as shortness of breath or swelling in your ankles or feet.