What Are Diuretics and Why are They Used in Sports and Bodybuilding?

Posted on 24 Feb 2011 02:36

By Ground Up Strength

A diuretic is any agent that acts to increase urine. Diuretics increase the excretion of water and electrolytes from the body's fluids. They thereby decrease the extracellular fluid volume. They are used to adjust the volume or composition of the body fluids in many different clinical situations such as high blood pressure, heart failure, renal failure and nephrotic syndrome. The common name for diuretic drugs are "water pills."

Diuretics generally work by affecting ion transport in the kidney nephron. The most clinically useful ones primarily decrease sodium (Na+) re-absorption] from the tubules. By putting more sodium into the urine diuretics take water along with them, which gets carried along passively so that osmotic equilibrium is maintained.

The Five major classes of diuretics are

  • Carbonic anydrase inhibitors - Acetazolamide (Diamox)
  • Loop diuretics - Forosemide (Lasix), ethacrynic acid (Edecrin), and bumetanide (Bumex), Torsemide (Demadex)
  • Thiazede diuretics - Chlorothiazide, Hydrochlorothiazide (Microzide), Indapamide, Metolazone (Zaroxolyn)
  • Osmotic diuretics - Mannitol and urea

Diuretic in Sports: Banned Masking Agents

Diuretics are part of the group of banned substances in sports known as "masking agents." These substances have no ergogenic (performance enhancing) effect of their own but are used to mask the presence of other banned substances. Other examples of masking agents are epitestosterone, probenecid, 5-alpha-reductase inhibitors and plasma expanders. Although these substances all have different mechanisms of action the primary objective is usually to reduce the concentration of the doping agent or its metabolites in the urine by some means. Diuretics have been banned by WADA since 1988. The idea is that diluting the urine makes the detection of banned substances in the urine more difficult.

Diuretic agents, however, can be detected in drug tests of urine. Also, despite how diluted the urine may be, the testing laboratory can simply concentrate the urine specimen, and adjust the pH, so that a drug test can be performed.

Diuretics are also used sometimes in sports with weight categories such as wrestling and boxing to lose weight quickly in order to be able to meet a weight requirement. This is another reason they are banned and a very dangerous practice.

Diuretics in Bodybuilding

Professional bodybuilders use diuretics several days before contests to help achieve the requisite "ripped and shredded" appearance. This is a big part of the judging standards in bodybuilding contests and the more defined the bodybuilder's muscularity, the better. The water shedding effect of diuretics helps rid their bodies of subcutaneous water (water beneath the skin). This essentially makes the skin thinner thus giving the muscle more clarity and definition. Although a very low body fat percentage is required to achieve the extremely defined muscles of modern bodybuilding the exquisite detail, complete with individual muscle striations, we see in today's bodybuilders, whether on stage during contests or in the pages of bodybuilding magazines, would not be possible without the use of these drugs which can be very dangerous.

Diuretics such as Lasix (Furosemide can have an immediate and fatal effect as they leach minerals and electrolytes from the body. Lasix is by far the most commonly known and can have such a potassium depleting effect if overused that cardiac arrest can occur. As it is "too potent" and hard to control it is likely to do much more than shed subcutaneous water and "deflate" the muscles as well, which contain mostly water themselves. This and the danger make drugs like Aldactone (Spironolactone), a milder potassium-sparing diuretic, more popular. Aldactone is an oral that comes in doses from 25 to 100 mgs per tablet and is claimed to only get rid of excess sodium but spare pottasium. Competitors will tend to limit sodium intake while using Aldactone. They will take supplementary minerals, such as potassium salts, and will even go so far as only drinking distilled water.

Some bodybuilders opt to use herbal diuretics, such as dandelion, which are available over-the-counter and bodybuilding supplement manufacturers market diuretic herbal preparations containing a mixture of diuretic herbs and extra magnesium, calcium, and potassium.


1. Ramachandran, Anand. "Chp. 23: Diurectics." Pharmacology Recall. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007. 194-201. Print.

2. Hemmersbach, Peter, and Detlef Thieme. "Chp. 15: Masking and Manipulation." Doping in Sports: Handbook of Experimemental Pharmocology. Vol. 195. Springer - International Publisher Science, Technology, Medicine. 327-29. Print.

This page is provided by Ground Up Strength for information purposes only and should not take the place of professional medical advice. Although we have done our utmost to provide accurate and safe information, we are not medical professionals and the information on this page should not be taken as professional medical advice, or any other kind of medical advice.

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