Hydrochlorothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention.

Olmesartan is in a group of drugs called angiotensin II receptor antagonists. Olmesartan keeps blood vessels from narrowing, which lowers blood pressure and improves blood flow.

The combination of hydrochlorothiazide and olmesartan is used to treat high blood pressure (hypertension).

Hydrochlorothiazide and olmesartan may also be used for purposes not listed in this medication guide.

You should not use this medication if you are allergic to olmesartan or hydrochlorothiazide (Carozide, Diaqua, Ezide HCTZ, HydroDiuril, Microzide, and others), or if you are unable to urinate.

Do not use this medication without telling your doctor if you are pregnant. Hydrochlorothiazide and olmesartan may cause injury and even death to the unborn baby if you take it during the second and third trimesters of pregnancy. Use an effective form of birth control. Stop using this medication and tell your doctor right away if you become pregnant during treatment.

Avoid drinking alcohol. It can lower your blood pressure and may increase some of the side effects of hydrochlorothiazide and olmesartan.

In rare cases, hydrochlorothiazide and olmesartan can cause a condition that results in the breakdown of skeletal muscle tissue, leading to kidney failure. Call your doctor right away if you have muscle pain, tenderness, or weakness especially if you also have fever, nausea or vomiting, and dark colored urine.

You should not use this medication if you are allergic to olmesartan or hydrochlorothiazide (Carozide, Diaqua, Ezide HCTZ, HydroDiuril, Microzide, and others), or if you are unable to urinate.

To make sure you can safely take hydrochlorothiazide and olmesartan, tell your doctor if you have any of these other conditions:

• kidney disease;

• liver disease;

• glaucoma;

• congestive heart failure;

• low or high levels of potassium in your blood;

• asthma or allergies;

• high cholesterol or triglyceride levels;

• gout;

• lupus;

• diabetes; or

• an allergy to sulfa drugs.

FDA pregnancy category D. Do not use this medication if you are pregnant. Stop using this medication and tell your doctor right away if you become pregnant. Olmesartan can cause injury or death to the unborn baby if you take the medicine during your second or third trimester. Use effective birth control while taking hydrochlorothiazide and olmesartan.

Hydrochlorothiazide and olmesartan can pass into breast milk and may harm a nursing baby. You should not breast-feed while you are using hydrochlorothiazide and olmesartan.