Thiazide or thiazide-like diuretics are commonly used to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.

Thiazide diuretics are also used to help reduce the amount of water in the body by increasing the flow of urine. They may also be used for other conditions as determined by your doctor.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For thiazide diuretics, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to sulfonamides (sulfa drugs), bumetanide, furosemide, acetazolamide, dichlorphenamide, methazolamide, or to any of the thiazide diuretics. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—When this medicine is used during pregnancy, it may cause side effects including jaundice, blood problems, and low potassium in the newborn infant. In addition, although this medicine has not been shown to cause birth defects or other problems in animals, studies have not been done in humans.

In general, diuretics are not useful for normal swelling of feet and hands that occurs during pregnancy. They should not be taken during pregnancy unless recommended by your doctor.

Breast-feeding—Thiazide diuretics pass into breast milk. These medicines also may decrease the flow of breast milk. Therefore, you should avoid use of thiazide diuretics during the first month of breast-feeding.

Children—Although there is no specific information comparing the use of thiazide diuretics in children with use in other age groups, these medicines are not expected to cause different side effects or problems in children than they do in adults. However, extra caution may be necessary in infants with jaundice, because these medicines can make the condition worse.

Older adults—Dizziness or lightheadedness and signs of too much potassium loss may be more likely to occur in the elderly, who are more sensitive than younger adults to the effects of thiazide diuretics.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary