This medication is used to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. This product contains two medications: lisinopril and hydrochlorothiazide. Lisinopril is an ACE inhibitor and works by relaxing blood vessels so that blood can flow more easily. Hydrochlorothiazide is a "water pill" (diuretic) that causes you to make more urine, which helps your body get rid of extra salt and water. This product is used when one drug is not controlling your blood pressure. Your doctor may direct you to take the individual medications first, and then switch you to this combination product. Do not continue taking the individual medications (lisinopril and/or hydrochlorothiazide) after you start this medication.