Written by Dan Gwartney, MD
09 April 2007
One of the most common complaints of a bodybuilder on the day of a show is "holding water." This term describes the blurring of muscular definition caused by a relative excess of extra-cellular water. Athletes in other sports, particularly those with weight classes or limits, will also complain of "holding water," referring to the extra pounds that might be shed through dehydration, rubberized sweat suits or non-stop spitting.
It is a common practice among these athletes to use a class of drugs called diuretics to shed the excess water. While diuretic use is most obvious in bodybuilding, its abuse is more prevalent in the sports of wrestling and horseracing (both the horses and jockeys), as well as the profession of modeling.

Diuretics drugs increase the amount of water lost through urinating. Most commonly used in the treatment of hypertension (high blood pressure), they may also be used to treat other medical conditions, providing lifesaving therapy in critical situations.1,2 Despite the benefits offered by diuretics, there are also definite risks, including sudden death. The choice to use diuretics should never be approached lightly. In fact, the wisest decision regarding diuretics would be never to use them at all. Bodybuilding has experienced tragedies, with athletes dying on and off stage. The single drug implicated in most bodybuilder deaths is a potent diuretic known as Lasix.

    Take Lasix, Pee Like a Racehorse
Lasix is the brand name for the drug furosemide, which is now marketed as a generic and may be manufactured under a variety of trade names.3 Contrary to common belief, the generic drugs, including those of foreign manufacture, have proven to be bioequivalent (containing the claimed amount of drug, with the same effect on the body).4-6 This makes Lasix, or an equivalent generic, a very inexpensive drug, particularly if purchased in Mexico. The low price of Lasix and the obvious effect of the drug (literally peeing like a racehorse) seem to have kept counterfeit products from infiltrating the black market.3
Diuretics act on the kidney through different mechanisms; some are milder and relatively safe, while others are extremely potent and carry greater risk. Lasix, as a member of the class called "loop diuretics," is one of the most powerful and dangerous diuretics used in the United States. Understanding how Lasix works requires a fairly extensive knowledge of kidney anatomy and physiology,1 but it can be explained in general terms sufficiently to appreciate the effect and risks inherent in this drug.

The kidney filters a number of waste products from the blood and clears out excess ions (or electrolytes). This is a critical function of the kidney, as it maintains blood pressure in a healthy, normal range when functioning properly. The ions may be excreted into the urine after being filtered, or they may be returned to the blood, depending upon the blood pressure. If it is high,   more ions are excreted (peed away). This reduces blood pressure by pulling more water into the urine, so the body dehydrates to a degree in order to reduce the blood pressure.1 The extracellular water comes from the plasma (the watery part of blood) and interstitial fluid. Interstitial fluid is the water that lies between cells, and accounts for the smooth look that blurs muscular definition. So, the advantage to bodybuilders of using diuretics is clear; it increases muscular definition by removing interstitial water.

The Price You May Pay
This does not come without cost. In the pool of urine created by the diuretic effect of Lasix, too many electrolytes can be lost, as the effect of the drug overpowers the natural balance maintained by an unadulterated kidney. In a very short time, a matter of hours, a person can enter into an electrolyte imbalance that can affect the function of the brain, muscles and heart.1,7-10 If the electrolyte imbalance is severe enough, the heart's rhythm becomes irregular and may stop. When the heart stops, the body dies... quickly.
Lasix blocks a transporter that returns sodium, potassium and chloride to the bloodstream from the filtered urine; it also causes the loss of calcium and magnesium ions.1,11-13 In the bloodstream and interstitial (between cells) fluid, there is a large supply of both sodium and chloride, so the loss of those two ions is not felt immediately. However, the amount of potassium is far less, so the loss of potassium is usually the immediate cause for Lasix-related injury or death. The loss of calcium and magnesium can contribute to the potassium-related damage and cause other serious problems.

The heart beats through a complex network of nerve-like fibers, carrying an electrical signal to the heart muscle. This electrical signal beats in a regular rhythm, and though the pace of the heartbeat may become quicker or slower, the underlying beat is always the same when the heart functions normally. This rhythm is created by a process called "depolarization" that is dependent upon the levels of potassium inside the cell, compared to the interstitial fluid (outside the cells). If the level of potassium in the interstitial fluid gets too high or too low, the electrical rhythm is disrupted and may stop altogether.10,14 It is similar to shorting out a battery. This is a life-threatening condition and can be very sudden, coming on without warning.

Risk Avoidance
Some bodybuilders are aware of the risks of potassium wasting associated with Lasix and try to correct for it by either combining Lasix with another diuretic, such as spirinolactone.15  Spironolactone is the prototype drug in a class of diuretics known as potassium-sparing diuretics.1 The two drugs combined will provide an additive effect, allowing for a greater diuretic effect (removing more interstitial water) without the risk of using higher doses of Lasix. There are diuretics on the market containing furosemide and spironolactone, such as the product Lasilactone.15

Other bodybuilders will attempt to correct for potassium wasting by supplementing with potassium. Potassium tablets can be purchased over the counter and are used in some patients who are on long-term diuretic therapy.1 However, recall that the heartbeat can be disturbed when potassium levels get too high, as well as too low.

The heartbeat is also sensitive to levels of magnesium in the blood, another ion lost during Lasix-induced diuresis. In fact, it's likely that the combination of low levels of both magnesium and potassium accounts for the rapid and severe effect on the heart's rhythm.13,16

Calcium, the final ion lost as a consequence of Lasix use, is involved in muscle contractions.12 If calcium levels drop, weakness or even tetany (a contraction which cannot relax, as in lockjaw) can occur. Obviously, this could lead to severe cramping or pain for a bodybuilder when posing onstage.
All of these effects can occur with the short-term use of diuretics as practiced by bodybuilders. Long-term use of diuretics has additional risks, including increased risk of cardiac (heart-related) death and altered drug metabolism.1,10,16,17 There is no benefit to any athlete of using diuretics for a long period, and there are several disadvantages, including poor exercise or heat tolerance, dehydration, weakness and circulatory collapse.

Drug Testing, NSAIDS Add to Risk
Drug testing, in the case of Lasix, has actually made a bad situation worse. Many bodybuilding events now test for diuretics, usually through urine samples submitted the night before or morning of a show. This forces the athlete using Lasix to inject the drug, hoping for a rapid effect, rather than using the slower, but "safer" Lasix tablets.3 Bodybuilders have injected Lasix prior to going on stage, only to suffer from cramps, fainting or death. The death of Andreas Munzer was at least partly, if not entirely, due to Lasix abuse. Given the great number of drugs he used at the same time, it is impossible to say if other drugs, such as erythropoietin, contributed to his premature death.18
Erythropoietin and most steroids increase the number of red blood cells that circulate in the blood. A high red blood cell mass, combined with a severely dehydrated state, would result in an unacceptably high hematocrit, turning the blood into sludge. This state would have made him prone to massive blood clots and diffuse bleeding. It is sad that the lesson learned from his costly example has not been sufficient to detract others from pursuing the same course.

One fact not discussed in the popular magazines or booklets, is that non-steroidal anti-inflammatory drugs (NSAIDs) will block or reduce the diuretic effect of Lasix.1,19-21 NSAIDs are very common, and used by most bodybuilders and other athletes. NSAIDs include aspirin, ibuprofen and naproxen (Bayer, Advil or Motrin and Aleve). Thus, any person who is considering using Lasix, whether he is testing his dosage during the pre-contest phase or immediately before a show, needs to be certain he's not using any drug or supplement containing NSAIDs. Certain "fat burners" contain white willow bark, which is a source of aspirin. A dose that seems to be effective while on NSAIDs, can be deadly when off the drugs.

    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.

References 
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18.    Kern B. Andreas Munzer's Death. Weights 1996 Apr 2;1215. Available through http://www.cyberiron.com/drugs/death.html accessed January 5, 2002.
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20.    Laiwah ACY, Mactier RA. Antagonistic effect of non-steroidal anti-inflammatory drugs on frusemide induced diuresis in cardiac failure. Br Med J 1981 Sep 12;283:714
21.    Wilkins MR, Woods KL. Effects of selective and non-selective inhibition of cyclo-oxygenase on furosemide stimulated natriuresis. Int J Clin Pharmacol Ther Toxicol 1986 Feb;24:55-7.