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

Metoprolol is a beta-blocker. Beta-blockers affect the heart and circulation (blood flow through arteries and veins).

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

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

You should not use this medication if you have severe or uncontrolled heart failure, a heart condition called "sick sinus syndrome" or "AV block," severe blood circulation problems, an adrenal gland tumor, an allergy to beta-blockers, or if you are unable to urinate.

Before using this medication, tell your doctor if you have congestive heart failure, kidney or liver disease, cirrhosis, glaucoma, asthma or bronchitis, gout, lupus, diabetes, a thyroid disorder, or if you are allergic to sulfa drugs or penicillin.

If you are diabetic, check your blood sugar carefully. Using metoprolol can make it harder for you to tell when you have low blood sugar. Your insulin or diabetic medication needs may change while you are taking hydrochlorothiazide and metoprolol. Talk with your doctor before changing any doses.

Drinking alcohol can further lower your blood pressure and may increase certain side effects of hydrochlorothiazide and metoprolol.

Avoid becoming overheated or dehydrated during exercise and in hot weather. Follow your doctor's instructions about the type and amount of liquids you should drink. In some cases, drinking too much liquid can be as unsafe as not drinking enough.

Keep taking this medication even if you feel fine. High blood pressure often has no symptoms.

There are many other medicines that can interact with hydrochlorothiazide and metoprolol. Tell your doctor about all the prescription and over-the-counter medications you use.

You should not use this medication if you are allergic to hydrochlorothiazide or metoprolol, or if you have:

• severe or uncontrolled heart failure;

• a heart condition called "sick sinus syndrome" or "AV block" (2nd or 3rd degree);

• severe blood circulation problems;

• an adrenal gland tumor (pheochromocytoma);

• if you are unable to urinate; or

• if you are allergic to any beta-blocker medication, such as atenolol (Tenormin, Tenoretic), carvedilol (Coreg), labetalol (Normodyne, Trandate), metoprolol (Dutoprol, Lopressor, Toprol), nadolol (Corgard), propranolol (Inderal, InnoPran), sotalol (Betapace), and others.

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

• congestive heart failure;

• kidney disease;

• liver disease (or cirrhosis);

• glaucoma;

• asthma or bronchitis;

• a thyroid disorder;

• lupus;

• gout;

• diabetes; or

• if you are allergic to sulfa drugs or penicillin.

FDA pregnancy category C. It is not known whether this medication will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

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