What is Tetrahydrogestrinone?

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  • Written By: Amanda Barnhart
  • Edited By: Michelle Arevalo
  • Last Modified Date: 17 February 2020
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Tetrahydrogestrinone (THG) is an anabolic steroid similar to gestrinone and trenbolone. Patrick Arnold developed the steroid for an American supplement company called Bay Area Laboratory Co-operative (BALCO) by making slight modifications to gestrinone and trenbolone. These changes made the drug undetectable in urine tests for many years, earning it the nickname The Clear.

BALCO has been investigated many times for allegations that the company supplied illegal steroids to athletes. On 18 October 2005, Victor Conte, the founder of BALCO, was sentenced to four months in prison and four months of house arrest for a plea agreement in a case involving his role in providing athletes with undetectable steroids, such as THG.

Anabolic steroids bind to androgen receptors in the body’s cells and encourage the growth of muscle tissue. Tetrahydrogestrinone has never been marketed commercially, but the drug was distributed among some top athletes in the United States and Europe. Tetrahydrogestrinone is an extremely potent steroid, and the drug was never approved for medical use.

The World Anti-Doping Agency prohibits the use of tetrahydrogestrinone for athletes, both in and out of competition. While the drug went undetected for several years, an anonymous track coach mailed a sample of the steroid to a doctor named Don Catlin, who was the director of the UCLA Olympic Analytical Laboratory in Los Angeles, in the summer of 2003. Dr. Catlin was able to analyze the substance and develop a detection method.


The United States Congress added tetrahydrogestrinone to the Anabolic Steroid Control Act of 2004, listing it as a Schedule III controlled substance. These are only legal to possess and use with a prescription from a doctor. Although some anabolic steroids have legitimate medical uses, doctors do not normally prescribe THG due to its potency and potentially dangerous side effects.

Using steroids for prolonged periods of time without the supervision of a medical professional can cause many negative side effects. Long-term use of steroids can lead to infertility, excessive hair growth, and can reduce the efficacy of the immune system. Anabolic steroids can also cause liver tumors, aggressive behavior, and may contribute to high total cholesterol levels.

No published medical studies have been conducted on the side effects THG because it was never developed for medicinal use. Because it is more potent than any commercially-available steroid, however, the side effects may be worse or may occur more quickly than they do in individuals who use medically-approved steroids under the supervision of a doctor.


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Post 3

@turkay1-- No one can get a hold of it now even if they wanted to. And you're right, THG is not necessarily better than other steroids. It does work a bit differently but I don't see why the same benefits could be attained by using just trenbolone.

Plus, THG is really toxic, much so than other steroids. It's not injected, it's absorbed by consuming orally and gets metabolized by the liver so it could cause liver damage if used in large amounts and regularly.

Post 2

@turquoise-- That's interesting. I never heard about it then but I guess the only reason THG became popular among competitive athletes was because it was undetectable.

Aside from this, tetrahydrogestrinone has no additional benefits compared to other steroids right? Considering that it has more side-effects and potential risks, I don't think anyone would bother to use it now.

Reading about how THG was able to get through testing without detection makes me wonder if there are other steroids out there that are not detected as well.

Sports doping is probably something that's always going to take place because there are new performance enhancing drugs and supplements coming out all the time. It's so dangerous though, especially if it's an unknown and untested drug.

Post 1

I remember when the whole THG issue happened in 2003. There was a coach who remains anonymous to this day who told the USADA about THG and even sent in a sample of it like the article said. Then "all hell broke loose" so to speak. USADA tested hundreds of American athletes to see if they were using THG.

I believe about 40 athletes were tested positive for THG. Several of these were actually preparing for the Olympics and were basically told that they would be disqualified to go if they didn't test negative for THG and other steroids before the competition. I don't remember if any athletes actually missed out on going to the Olympics because of THG but I know that this whole incident was talked about for a long time.

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