Lasix is not a hormone compound but a diuretic. Lasix belongs to the group of saluretics and to be exact is a loop diuretic. Lasix effect consists of distinctly increased excretion of sodium, chloride, potassium, and water. A very important characteristic which must be absolutely monitored with loop diuretics is the reabsorbtion of potassium ions, sodium ions, and chloride ions. This causes a considerable disturbance of the electrolyte household. Due to its intense effect on water excretion Lasix is used for treatment of edemas and high blood pressure. Bodybuilders use Lasix shortly before a competition to excrete excessive, mostly subcutaneous, water so that they appear hard, defined, and ripped to the bone when in the limelight. The effect of tablets begins within an hour and continues for 3-4 hours. Depending on how much water is still in the athlete's body he must have more or less frequent access to a restroom. This can cause a considerable weight loss within a very short time. For this reason, athletes often use Lasix to lose weight and to compete in a lower weight class.

The amount of the dosage, the duration of application, and the intervals of intake usually depend on the diuretic effect or the athlete's shape. Bodybuilders usually take a half or whole 40 mg Lasix tablet and wait to see what happens. Some repeat this procedure once or twice in an interval of a few hours. Lasix is the strongest diuretic and the most dangerous compound in bodybuilders' arsenal of medicine.

Side effects can include circulatory disturbances, dizziness, dehydration, muscle cramps, vomiting, circulatory collapse, diarrhea, and fainting. In extreme cases cardiac arrest is possible. Extreme caution is advised when athletes who are already substantially drained and dehydrated continue their loop diuretic treatment with a "make it or die attitude" or even continue the intake altogether with a completely reduced liquid intake.