Furosemide is an extremely potent and dangerous diuretic with the potential for serious side effects. It is available in both an oral form and as an injectable. Furosemide can cause dehydration and a reduction in blood volume which can lead to circulatory collapse and possibly stroke and can result in kidney damage. Furosemide can deplete potassium and sodium levels resulting in dangerous heart arrhythmias. Calcium can also become depleted resulting in severe muscle cramping and tetanus (freezing). Furosemide is used by competitive athletes to drop weight to stay in a weight class and by bodybuilders to reduce subcutaneous water before a competition. The use of furosemide is extremely dangerous and should not be used without medical supervision.