Zestoretic contains a combination of hydrochlorothiazide and lisinopril. Hydrochlorothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention. SIDE EFFECTS. ZESTORETIC has been evaluated for safety in 930 patients including 100 patients treated for 50 weeks or more. In clinical trials with ZESTORETIC no adverse experiences peculiar to this combination drug have been observed. Captopril is an oral drug and a member of a class of drugs called angiotensin converting enzyme (ACE) inhibitors. ACE inhibitors are used for treating high blood pressure, heart failure, and for preventing kidney failure due to high blood pressure and diabetes. Hydrochlorothiazide (Microzide and others) is a drug used to treat excessive fluid accumulation and swelling (edema) of the body caused by heart failure, cirrhosis, chronic kidney failure, corticosteroid medications, and nephrotic syndrome. Side effects, dosage, drug interactions, and pregnancy and breastfeeding safety are provided. Lisinopril/hydrochlorothiazide (Zestoretic) is an oral medication used to treat high blood pressure. Learn about side effects, warnings, dosage, and more. Melatonin is a hormone that's naturally found in the body. A synthetic version of melatonin is available as a supplement that's used to treat sleep disorders and other problems. Lisinopril is a prescription medication used to treat high blood pressure (hypertension) in both adults and children 6 years of age and older. By medical definition, high blood pressure is a condition that is defined as a repeatedly elevated blood pressure. Note: This document contains side effect information about hydrochlorothiazide / lisinopril. Some of the dosage forms listed on this page may not apply to the brand name Zestoretic. Potassium is a mineral that is found in many foods and is needed for several functions of your body, especially the beating of your heart. Potassium citrate is used to treat a kidney stone. Initially, 1 tablet daily of either the 10—12.5 or 20—12.5 mg dosage ratio of lisinopril and HCTZ, when blood pressure is not responsive to lisinopril or hydrochlorothiazide (HCTZ) monotherapy.