Diuretics, also known as water pills, are medicines that help reduce the amount of water in the body. They treat the buildup of excess fluid in the body that occurs with some medical conditions such as congestive heart failure, liver disease, and kidney disease. Some diuretics are also prescribed to treat high blood pressure. They act on the kidneys to increase urine output, reducing fluid in the bloodstream, in turn lowering blood pressure.

There are several types of diuretics. Loop diuretics, such as bumetanide (Bumex) and furosemide (Lasix), get their name from the loop-shaped part of the kidneys where they have their effect. Thiazide diuretics include such commonly used diuretics as hydrochlorothiazide (HydroDIURIL, Esidrix), chlorothiazide (Diuril), and chlorthalidone (Hygroton). Potassium-sparing diuretics prevent the loss of potassium, a problem with other type pes of diuretics. Examples are amiloride (Midamor) and triamterene (Dyrenium). In addition, some medicines contain combinations of...