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

Chlorthalidone treats fluid retention (edema) in people with congestive heart failure, cirrhosis of the liver, or kidney disorders, or edema caused by taking steroids or estrogen. This medication is also used to treat high blood pressure (hypertension).

Chlorthalidone may also be used for other purposes not listed in this medication guide.

Do not use this medication if you are allergic to chlorthalidone or if you are unable to urinate.

Before using this medication, tell your doctor if you are allergic to sulfa drugs, or if you have liver disease, kidney disease, asthma, allergies, gout, lupus, or diabetes.

Avoid drinking alcohol, which can increase some of the side effects of chlorthalidone.

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.

If you are being treated for high blood pressure, keep using this medication even if you feel fine. High blood pressure often has no symptoms.

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

If you have any of these conditions, you may need a dose adjustment or special tests to safely take this medication. Before using chlorthalidone, tell your doctor if you have:

• kidney disease;

• liver disease;

• asthma or allergies;

• gout;

• lupus;

• diabetes; or

• if you have an allergy to sulfa drugs.

FDA pregnancy category B. This medication is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

Chlorthalidone can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.