Bodybuilder’s Lasix Guide

The following information was taken from an article written by Steven Smi from – the original article can be found here


Diuretics are drugs that can increase the amount of water and sodium that is excreted in the urine. There are several classes of diuretics, each with a different mechanism of action.

Types of Diuretics

There are three main types of diuretics; potassium-sparing, osmotic and loop diuretics:

  • Osmotic Diuretics – These are injectable drugs that act on the kidneys by essentially instructing the kidneys to release everything that comes in. Osmotic diuretics are non-discriminatory, meaning they remove any and all water that comes to the kidneys, regardless of proper electrolyte balance. These drugs override the function of the kidneys and can cause renal (kidney) failure. Osmotic diuretics are not overly common in bodybuilding.
  • Potassium-sparing Diuretics – These diuretics are milder, however create problems of their own. They reduce the re-absorption of sodium and water through the kidneys and flush them out of the body. They do, however discriminate by not flushing potassium(K) from the system. While these are slower acting and more tolerable, they can cause an excess of K in the body as they do not allow it to flush and keep the balance of electrolytes intact. This can cause, in extreme cases, cardiac dysrythmia (irregular heartbeats) and even sudden death in the most extreme cases.
  • Loop Diuretics – These are far and away the most commonly used diuretics in bodybuilding and the culprit in the vast majority of bodybuilding hospitalizations and deaths. Furosimide (brand name Lasix) is easily the most widely used loop diuretic and is cheap and readily available. Loop diuretics are used medicinally to treat high blood pressure and edema; and in cases of blood poisoning are used to flush the blood of toxins and foreign agents. Loop diuretics act directly on the kidneys and are another non-discriminatory diuretic in that they remove any and all fluids coming through the kidneys. They have a profound effect on the electrolyte balance as they literally flush potassium, sodium and calcium from the body with whatever fluid enters. Side effects include a drop in blood pressure, thickening of the blood (due to lack of fluids), fainting, renal failure, extreme cramping due to electrolyte imbalances, and death (due to muscular cramping of the heart). The drug is extremely powerful and, combined with other water reduction techniques employed by bodybuilders in contest preparation, it doesn’t take much Lasix to cause extremely detrimental health effects.


Lasix is the brand name for the drug Furosemide, which is a prescription based diuretic drug. As mentioned above, it is a loop diuretic, which is on the World Health Organization’s (WHO) list of essential medicines. These are the most important medications needed for basic medicinal purposes.

Lasix was approved by the FDA in 1982. Currently, the French pharma company Sanofi markets Furosemide under three brand names: Lasix, Fusid, and Frumex.

Leading up to competitions, bodybuilders have used this drug as a diuretic to flush out excess water.


Medical Uses in Humans

Lasix is an important drug used for treatment of hypertension and edema, which is an abnormal accumulation of fluid in the cavities of the body beneath the skin.

Other medical uses include:

  • Hepatic cirrhosis
  • Renal impairment
  • Nephrotic syndrome
  • Severe hypercalcemia

How it Works

Lasix will eliminate water and salt from the body very quickly. In the kidneys, salt, water, and other molecules are filtered out of the blood and into the tubules of the kidney; this fluid becomes urine. Most of the substances are reabsorbed into the blood before the filtered fluid becomes urine. Lasix works by blocking the absorption of the sodium, chloride, and water from the filtered fluid in the kidney tubules, causing an increase of urine output (diuresis). For more information on the science behind diuretic drugs, click here.

Half Life

The half life of Lasix is listed as 2 hours. However, it is important to remember half life does not mean duration of how long the drug will work in the body. Injectable lasix will start working within minutes and the duration of diuresis is 2 hours. On the other hand, the oral version acts within an hour and lasts for about 6-8 hours. Significantly more Lasix is excreted in urine following IV injections than after the tablet solution.

Dosage for Medical Patients

There is an oral and IV/IM version of Lasix available. Depending on the patients medical condition and weight, the dosages will vary and a doctor will decide how best to proceed. For normal adults, 20-80mg dosage will cause prompt diuresis, and then a followup dosage is done 6-8 hours later. In patients with severe edema, dosages can go as high as 600mg per day, due to the absence of kidney functions (since it is a loop diuretic).

Bodybuilding and Dosages

Lasix is used by bodybuilders shortly before competitions, and sometimes up to two days beforehand, to excrete excessive water so that they appear hard, defined, and have a ripped physique on stage.

The oral version of the compound is most popular with bodybuilders, but some athletes will use injections the morning of the competition. It is important to time Lasix perfectly or the muscles can become small and flat, and vascularity will be lost. In addition, you must have easy access to a restroom to urinate out the water.

If too much blood volume is lost, the bodybuilder may have to inject glucose solution intravenously to offset that loss. Potassium levels will also drop, so it’s wise to keep potassium tablets on hand. However, they should be used with extreme care, as too much potassium can be deadly.

The exact dosages with diuretics will vary, so the athlete must experiment to get just the right amount, or it can become counter productive. A good strategy is to start with 10-20mgs then asses the tolerance levels, and go from there. With Lasix, more is definitely not better, and if this powerful diuretic is abused. it can lead to hospitalization and even death.

Another strategy that is implemented deals with combining diuretics. Since Lasix has such a powerful effect on electrolyte and potassium levels, stacking it with a potassium sparing compound like Aldactone is synergetic. A stack of 50mg of aldactone and 20mg lasix is popular.

Lasix should ONLY be used by the most experienced bodybuilders. I don’t suggest it to new guys. This stuff can be deadly when abused, and bodybuilders have died after taking too much diuretics.

Side Effects

As you can imagine, a powerful diuretic can be very dangerous and the side effects are plentiful. If these symptoms begin, medical care may be needed. Some of the most common side effects:

  • Dizziness
  • Headache
  • Dry Mouth
  • Gastrointestinal Discomfort
  • Low Urine Volume
  • Muscle Cramps
  • Low Blood Pressure
  • Seizures

As mentioned, a potassium supplement (not overdosed) is important to keep on hand. While it is possible to experience these side effects of Lasix in a non-life threatening manner, we’re not quite out of the woods yet. The possible side effects of Lasix can get much worse. We cannot call the following effects extremely common but they are also far from uncommon. The serious side effects of Lasix include:

  • Pancreatitis
  • Vomiting
  • Nausea
  • Loss of Hearing
  • Anemia
  • Decreased White Blood Cell Count
  • Dermatitis
  • Rash
  • High Blood Sugar
  • Muscle Spasms
  • Fever
  • Blood Clot
  • Large Buildups in Uric Acid in the Blood

The Tragic

Throughout the history of bodybuilding there have unfortunately been several deaths and multiple hospitalizations due to contest preparation and standard bodybuilding practices. These hospitalizations and deaths are rarely due to steroids and other hormones, lifting injuries, powerful stimulant based fat-burners or highly restrictive diets. In fact, there is no direct evidence connecting the use of anabolic steroids to the death of any athlete, only indirect or circumstantial evidence. Rather, most hospitalizations and deaths are, in fact, overwhelmingly due to the use and abuse of diuretic drugs. Some of the most famous instances include:

In 1988, pro bodybuilder Albert Beckles collapses and convulses while on stage. He is subsequently resuscitated by paramedics and found to be suffering from diuretic-induced dehydration.

In 1992, pro bodybuilder Mohammed Benaziza dies after competing in a contest in Europe. An autopsy shows that he was severely dehydrated and experienced cardiovascular failure. He was age 33. He had used a combination of diuretics for the show.

In 1994, pro bodybuilder Paul Dillett cramps onstage while posing at the Arnold Classic. He is carted off the stage. Once again, the problem was extreme dehydration and electrolyte imbalance caused by Paul’s use of Lasix. Paul survived.

There was also the 1996 case of Andreas Munzer, renowned for his freaky conditioning, who died after his liver and kidneys failed. The autopsy revealed his electrolytes were completely out of balance.

These are just the most publicized cases; numerous other deaths and hospitalizations didn’t get any publicity at all.

Availability of Lasix

Lasix is widely available on the prescription and black markets. While Lasix is merely a brand name, you will find Furosemide is extremely easy to find under numerous brand names and also generically. Counterfeits are virtually unheard of and you will find anabolic steroid suppliers commonly carry the diuretic. You will also find the compound is commonly available in 10mg and 20mg tablets, but there’s another version you need to be aware of. There are 500mg Lasix tablets available. They are not commonly found outside strictly regulated medical use but they can be found. This is a tablet that should be avoided at all cost by most all people and should not be used by any athlete. Large dose 500mg Lasix tablets should only be used in severe medical conditions and will kill most that use them. An athlete who uses a 500mg Lasix tablet will more than likely die.


Lasix was placed on the World Anti Doping Agency’s banned drug list due to its use as a masking agent for other drugs. Using lasix in WADA tested competitions will likely lead to a suspension.

Trade Names:

  • Diurapid
  • Durafurid
  • Fumarenid
  • Furon
  • Furomin
  • Furomex
  • Furosemide
  • Lasix
  • Fusid
  • Impugan
  • Jenafusid
  • Semid
  • Seguril
  • Vesix
  • Sigasalur
  • Trofurit

Summing Up

Lasix is a popular and potent “loop diuretic” that can pull off vast amounts of retained water for a short period, providing bodybuilders the “ripped” look they strive so hard to achieve. It works on the kidney by blocking the return of electrolytes to the bloodstream, causing more water to be passed in the urine, water which is taken from the bloodstream and the spaces between cells (interstitial spaces). It is interstitial water that blurs muscular definition. Unsafe use of Lasix can result in the loss of excess potassium and magnesium, which can cause an irregular heartbeat and sudden death. Even low doses of the drug in a dehydrated person can cause “thickened blood” (a high hematocrit) or circulatory collapse (usually due to blood pressure dropping too low). Some users have found that low doses of Lasix, used with either a potassium-sparing diuretic or a potassium supplement, prevent cramping and other Lasix-related problems. It is likely that the sport of bodybuilding will continue to see diuretic-related problems, as the competitors are turning to fast-acting injectable versions of Lasix during the short period of drug testing and competition.

Lasix may seem like a reasonably safe drug, as it is merely a diuretic and not a potent hormone or stimulant. However, it has proven to be the deadliest drug bodybuilding has yet seen. No one should consider using Lasix without also considering the high risk of injury or death.

Buying Lasix

I use – they stock pharmaceutical grade Lasix. Shipping to the UK usually takes 1-2 days and they do ship internationally too. Just send them an email explaining that you got their email address from this website and ask for a price list and they will send over a full list of products and prices.

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