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

Hydralazine is a vasodilator that works by relaxing the muscles in your blood vessels to help them dilate (widen). This lowers blood pressure and allows blood to flow more easily through your veins and arteries.

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

Hydrochlorothiazide and hydralazine is usually given after other blood pressure medications have been tried without successful treatment.

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

You should not use this medication if you are allergic to hydralazine (Apresoline) or hydrochlorothiazide, or if you have coronary artery disease, rheumatic heart disease affecting the mitral valve, or if you are unable to urinate.

Before using this medication, tell your doctor if you have liver disease, kidney disease, glaucoma, angina pectoris (chest pain), asthma or allergies, gout, lupus, diabetes, an allergy to sulfa drugs or penicillin, or if you have ever had a stroke.

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

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.

There are many other drugs that can interact with hydrochlorothiazide and hydralazine. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor. Keep a list of all your medicines and show it to any healthcare provider who treats you.

Keep using this medicine as directed, even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medication for the rest of your life.

You should not use this medication if you are allergic to hydralazine (Apresoline) or hydrochlorothiazide, or if you have:

• coronary artery disease;

• rheumatic heart disease affecting the mitral valve; or

• if you are unable to urinate.

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

• kidney disease;

• liver disease;

• glaucoma;

• angina pectoris (chest pain);

• asthma or allergies;

• gout;

• lupus;

• diabetes;

• an allergy to sulfa drugs or penicillin; or

• if you have ever had stroke.

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

It is not known whether hydrochlorothiazide and hydralazine passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are using hydrochlorothiazide and hydralazine.