Furosemide, which is sometimes sold under the brand name Lasix, is not a potassium-sparing diuretic, according to Mayo Clinic. It is a loop diuretic in the same class as bumetanide, torsemide and ethacrynic acid. Furosemide works by making the kidneys expel more sodium into the urine, which has the effect of pulling more water along with it and reducing overall fluid volume in the body.
There are three types of diuretics: loop diuretics, such as furosemide, thiazide diuretics, such as hydrochlorothiazide, metolazone and indapamide, and potassium-sparing diuretics, such as triamterene, spironolactone and eplerenone. Some medications feature more than one type of diuretic combined into one formula.
Thiazide diuretics may be given as a first-line treatment for high blood pressure and hypertension-related heart problems. They may also be useful in preventing, improving or treating other conditions, including heart failure, polycystic ovary syndrome, edema, and osteoporosis. Other conditions for which diuretics may be used include kidney disorders, diabetes, and male pattern hair growth in women.
Mayo Clinic cautions that people taking potassium-sparing diuretics may develop hyperkalemia, which is a condition where there is too much potassium in the blood. Those taking thiazide diuretics may develop hypokalemia, which is too little potassium in the blood.