Generic Name: furosemide (fur OH se mide) Brand Names: Lasix, Lo-Aqua What is furosemide? Furosemide is a loop diuretic (water pill) that prevents your body from absorbing too much salt, allowing the salt to instead be passed in your urine. Furosemide treats fluid retention (edema) in people with congestive heart failure, liver disease, or a kidney disorder such as nephrotic syndrome. This medication is also used to treat high blood pressure (hypertension). Furosemide may also be used for purposes other than those listed in this medication guide.