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

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

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

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

Do not use hydrochlorothiazide and telmisartan if you are pregnant. Stop using this medication and tell your doctor right away if you become pregnant.

Do not use this medication if you are allergic to hydrochlorothiazide or telmisartan, or if you are unable to urinate.

Before using hydrochlorothiazide and telmisartan, tell your doctor if you have congestive heart failure, kidney or liver disease, glaucoma, asthma, low or high blood levels of potassium, gout, lupus, diabetes, or an allergy to sulfa drugs or penicillin.

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

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.

Do not use potassium supplements or salt substitutes while you are taking hydrochlorothiazide and telmisartan, unless your doctor has told you to.

In rare cases, hydrochlorothiazide and telmisartan 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 unexplained muscle pain, tenderness, or weakness especially if you also have fever, unusual tiredness, and dark colored urine.

You should not use this medication if you are allergic to hydrochlorothiazide or telmisartan, or if you are unable to urinate.

To make sure you can safely take this medication, tell your doctor if you have any of these other conditions:

• kidney disease;

• liver disease;

• congestive heart failure;

• glaucoma;

• asthma or allergies;

• low or high levels of magnesium or potassium in your blood;

• gout;

• lupus,

• diabetes; or

• an allergy to sulfa drugs or penicillin.

FDA pregnancy category D. Do not use hydrochlorothiazide and telmisartan if you are pregnant. Stop using this medication and tell your doctor right away if you become pregnant. Hydrochlorothiazide and telmisartan 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 telmisartan.

It is not known whether hydrochlorothiazide and telmisartan passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.