Clenbuterol (also called “clen”) is an asthma medicine, as in most countries is used to treat respiratory diseases in horses.

Clenbuterol is on the doping list and got “world famous” when the German sprinter Katrin Krabbe tested positive for clenbuterol. A three-year suspension for taking clenbuterol from competing in the 1992 Summer Olympics, and effectively ended her athletic career.

American swimmer Jessica Hardy tested positive at the US trials in 2008.


In Norway there is the name Ventipulmin. As far as we know the horses need this drug is used in so-called “exemption from registration”. That means treating doctor (veterinarian) must prescribe the drug for a particular patient (horse) or to use at their office (stall).


Beginning November 1, 2015, clenbuterol was considered a forbidden drug for horses per AQHA Rule VIO401. Earlier that year, positive drug tests for detection of clenbuterol in American Quarter Horse Association (AQHA) racehorses resulted in significant penalties. As previously announced April 24 2015, that policy was expanded to put an end to the abusive use of clenbuterol in show horses, and in time for the 2015 AQHA World Championship Show.


A bronchodilator marketed as Ventipulmin, clenbuterol is a legitimate and valuable medication used by veterinarians to treat horses with breathing difficulties, but its use has gotten completely out of hand because of its ability to act as a beta-2 agonist to increase muscle mass when used in dosages exceeding recommended amounts.


Although clenbuterol use in livestock is now banned in the U.S. and much of Europe, it has been used to increase the lean mass and the overall yield of livestock production.

Tour de France cycling race stage 19

Photo: Alberto Contador (ESP) punched a spectator during Stage 19 of the Tour de France 2010.

Because of this, some athletes who test positive for clenbuterol often claim they must have eaten contaminated meat. Three-time Tour de France winner Alberto Contador may be the most famous athlete to claim his positive clen test was due to eating meat from an animal treated with clenbuterol. He was banned for two years from professional cycling after testing positive for the drug at the 2010 Tour de France.

Also Jamaican athletes in Beijing Olympic 2008 has claim this, and was beleaved that they had got this from Chinese meat.

In 2013, Contador’s team-mate on the Team Saxo Bank squad, Michael Rogers, tested positive for clenbuterol at the Japan Cup bike race. In April 2014 the Union Cycliste Internationale announced that it accepted Rogers’ explanation that the substance had been ingested by him after consuming contaminated meat whilst competing at the 2013 Tour of Beijing, upholding Rogers’ disqualification from the Japan Cup but declining to impose any further sanctions on him.

In 2011, players of the Mexico national football team were found with clenbuterol in their bloodstreams, but were acquitted by WADA after they claimed the clenbuterol came from contaminated food. FIFA has also claimed 109 players from multiple countries who were participating in the Under-17 World Cup in Mexico tested positive for this drug. However, FIFA and the World Anti-Doping Agency declined to prosecute any cases because the weight of evidence pointed to contamination from Mexican meat.

In 2013, Mexican boxer Erik Morales was suspended for two years after testing positive for clenbuterol.

In 2014, Czech body builder Petr Soukup (photo under from 2004) received a lifetime ban after a positive test for this “drug-coctail“;  clenbuterol, metenolon, mesterolon, methamphetamine, oxandrolon, stanozolol, nandrolon, fluoxymesterone, DHCMtestosterone and metandienon. World record in taken drugs?


China’s national team athletes headed for the London Games 2012 was order to stop eating many forms of Chinese meat, due to fears that they could consume the banned substance clenbuterol. The background for this was The Chinese’s General Administration of Sport issued the urgent demand after Chinese Olympic judo champion Tong Wen (photo under) was slapped with a two-year ban when traces of the prohibited performance-enhancing substance was found in her bloodstream.
The International Judo Federation banned Tong on May 10, 2010, and she was required to give back her gold medal from the World Championships of 2009.
The punishment set alarm bells ringing that other top stars might fail drug tests and be stopped from competing at the Games if they, too, are found with clenbuterol in their systems.


Many athletes continue using clenbuterol to burn fat, build muscle and improve sports performance. Even though clenbuterol use is banned in most organized sports competitions, many athletes are still found using the substance.

Not just athletes are affected by contamination. In Portugal, 50 people were reported as affected by clenbuterol in liver and pork between 1998 and 2002, while in 1990, veal liver was suspected of causing clenbuterol poisoning in 22 people in France and 135 people in Spain.

In September 2006, over 330 people in Shanghai were reported to have food poisoning by eating clenbuterol-contaminated pork that had been fed to the animals to keep the meat lean.

In February 2009, at least 70 people in one Chinese province (Guangdong) suffered food poisoning after eating pig organs believed to contain clenbuterol residue. The victims complained of stomachaches and diarrhea after eating pig organs bought in local markets.


Clenbuterol is used as asthma medicine on humans in some European countries. Spain comes as no bomb, but it is also used in Germany, Italy and Austria.
In Spain Spiropent from Euro Pharma (Boehringer Ingelheim) most familiar. The obtained tablet and liquid Mixtur. Previously, it was no problem to buy such drugs without prescription in Spain, but it would appear that there will be stricter there, too.


Clenbuterol is a “sympathomimetic” that affects the sympathetic nervous system. This occurs by stimulation of β2-adrenergic receptors.
These receptors exist in the heart, lungs, digestive tract, liver, pancreas and skeletal muscle.
There are three known types of beta receptors. β1, β2 and β3. Clenbuterol is a selective β2 agonist.
This means that Clenbuterol primarily stimulate β2 receptors, and not β1 or β3 receptors.
But unfortunately also affects Clenbuterol β1 receptors. These are found in the heart, kidneys, adipose tissue and central nervous system.

In general, the positive effects of clenbuterol seem to be short-lived. The effects of long-term clenbuterol intake on an athlete’s performance, muscle strength and overall heart health are still unclear.


In 2005 received a 17-years old in Poland heart attack after using Clenbuterol. Studies have shown that clenbuterol may lead to cell death or apoptosis in the muscles, incl. damage the heart.
This may be because Clenbuterol stimulates β1 receptors in the heart, which will seem stressful on the heart muscle
It is also reported myocardial infarction in a bodybuilder whose combined anabolic steroids and clenbuterol, where it seems that these substances together could be the reason infarction.

Other side effects by using Clenbuterol may cause cardiac hypertrophy (enlargement of heart ventricles), a potentially serious form of heart damage as mention, as well as irregular rhythms, and as stated above, specific cell death. Other side effects of “clen” use may include muscle tremors, increased perspiration, increased blood pressure, insomnia, headache, nausea and vomiting.


For those of you who have heard about “beta-blockers” so making such drugs the opposite of Clenbuterol.
Beta blockers inhibit the action of artificial and endogenous (endogenous) catecholamines such as adrenaline, noradrenaline and dopamine by acting as antagonist of β-adrenergic receptors in the sympathetic nervous system.