This drug is used to treat high blood pressure (hypertension). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. This product contains two medications: irbesartan and hydrochlorothiazide. Irbesartan is an angiotensin receptor blocker (ARB) 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.