Furosemide: learn about side effects, dosage, special precautions, and more on MedlinePlus. Why is this medication prescribed? Expand Section. Lasix may be used with antihypertensive drugs to control high blood pressure ( hypertension). Lasix is available as a generic. Side effects of Lasix include. Furosemide is a type of medicine called a diuretic. It's used to treat high blood pressure, heart failure and oedema (a build up of fluid in the body). It's also.