The combination of triamterene and hydrochlorothiazide is used to treat high blood pressure and edema (fluid retention; excess fluid held in body tissues) in patients who have lower amounts of potassium in their bodies or for whom low potassium levels in the body could be dangerous. The combination of triamterene and hydrochlorothiazide is in a class of medications called diuretics ('water pills'). They work by causing the kidneys to get rid of unneeded water and salt from the body into the urine. High blood pressure is a common condition, and when not treated it can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.