Triamterene is used to reduce extra fluid in the body (edema) caused by conditions such as congestive heart failure, liver disease, and kidney disease. Getting rid of extra water helps to reduce fluid in the lungs so that you can breathe easier. It also helps to decrease swelling of the arms, legs, and stomach/abdomen.
Triamterene is a certain kind of "water pill" (potassium-sparing diuretic). It works by increasing the amount of urine you make, allowing your body to get rid of extra salt (sodium) and water while also preventing the kidneys from getting rid of too much potassium.