Furosemide is used for:

Treating fluid build-up and swelling caused by congestive heart failure, liver cirrhosis, or kidney disease. It is also used in combination with other medicines to treat fluid build-up in the lungs. It may also be used for other conditions as determined by your doctor.

Furosemide is a loop diuretic. Loop diuretics make the kidneys eliminate larger amounts of electrolytes (especially sodium and potassium salts) and water than normal (diuretic effect). Loop diuretics are useful for treating many conditions in which salt and water retention (eg, edema, swelling) is a problem...