Zestoretic is used to treat high blood pressure (hypertension). It contains two medicines called lisinopril and hydrochlorothiazide.•Lisinopril belongs to a group of medicines called ACE inhibitors. It works by making your blood vessels widen.•Hydrochlorothiazide belongs to a group of medicines called diuretics (water tablets). It helps your body to get rid of water and salts like sodium in your urine. These medicines work together to lower your blood pressure.