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Clenbuterol and Meat Contamination

Originally released April 2011
Updated June 2021

The use of clenbuterol as a growth promoting substance in animal husbandry (beef, pork, lamb or poultry) in Mexico, China, and Guatemala has led to numerous positive anti-doping tests over the past decade. With many of these cases resulting in no fault violations because athletes unknowingly consumed meat contaminated with clenbuterol in or from these high-risk countries, the World Anti-Doping Agency (WADA) has established new rules effective June 1, 2019 to ensure that clenbuterol meat contamination cases are resolved in a way that’s most fair to the athlete.

Keep reading to learn more about clenbuterol and how meat contamination cases are now being managed under the current rules:


What is clenbuterol and meat contamination?

Clenbuterol is an anabolic agent sometimes used for performance-enhancement by athletes to increase lean muscle mass and reduce body fat. In some countries, clenbuterol has also been used to promote muscle mass and meat yield, including cattle, lamb, poultry, and swine. Such use is illegal in the U.S. and in Europe, but reports have shown that it does occur in other countries, including China, Mexico, and Guatemala.

Clenbuterol administration to animals destined for food production can result in, under specific conditions, a positive sample from an athlete. WADA has issued specific warnings about this problem in China and Mexico. Unfortunately, anti-doping authorities have no control over agricultural and food safety practices in these countries, and inadvertent ingestion remains an ongoing issue for athletes.


Is clenbuterol prohibited in sport?

Clenbuterol is prohibited under the category of Anabolic Agents on the WADA Prohibited List because it promotes muscle growth through anabolic properties.

Clenbuterol is not legally distributed in the U.S. and is not approved by the Food and Drug Administration (FDA) for human or veterinary use. Athletes should also be aware and use extreme caution knowing that clenbuterol may still be prescribed clinically by physicians in some countries as a bronchodilator beta-2 agonist medication.


How are clenbuterol and meat contamination cases handled under anti-doping rules?

WADA has concluded through scientific research that an athlete can test positive for clenbuterol at low levels after consuming contaminated meat, leading the organization to review international results management rules around clenbuterol positives.

Effective June 1, 2019, a new amendment was introduced by WADA stating that low levels of clenbuterol (urine concentrations < 5 ng/mL) present in an athlete’s sample can be reported by a WADA-accredited laboratory as an atypical finding and investigated as a potential meat contamination case.

This will ensure that valid meat contamination cases are dealt with fairly and may prevent athletes from receiving an Anti-Doping Rule Violation and having their competition results disqualified as a result of eating contaminated meat. In such instances, and with proper documentation and supporting evidence, the circumstances will be reviewed to determine if a non-doping explanation exists for the athlete’s positive test.

If clenbuterol is detected at or above 5 ng/mL, the standard results management process will be followed.

In response to the global occurrence of positive tests shown to be the result of contaminated medications and meat, a group of scientific and legal experts made specific recommendations to WADA to establish Minimum Reporting Levels (MRLs) for selected diuretics and anabolic steroids/growth promoters detected in urine samples by WADA-accredited laboratories. Starting June 2021, WADA implemented MRLs for a number of prohibited diuretics (namely, acetazolamide, bumetanide, furosemide, hydrochlorothiazide, torasemide, and triamterene), and livestock growth promotors (namely,  clenbuterol, ractopamine, zilpaterol, and zeranol ), and will continue to evaluate the need for MRLs for additional compounds should they be directly associated with contamination. For certain sports or in certain circumstances, results below the MRLs will trigger an investigation by the relevant anti-doping authority to try to determine the source and circumstances around the ingestion or exposure to the prohibited substance. To read more, please see WADA’s statement.


How can athletes reduce their risk of consuming contaminated meat?

USADA urges athletes to use the utmost care and caution if eating meat while traveling abroad, and to be aware of the potential for contamination. To USADA’s knowledge, due to strict regulatory and meat certification practices, a clenbuterol positive athlete sample has never been reported after consumption of meat produced in the U.S.

To reduce your risk of unintentionally ingesting a prohibited substance through contaminated meat:

  • Choose meat from a reputable source (e.g., athlete village, hotel, etc.).
  • Inquire where meat products are sourced from at hotels and restaurants (imported meats from the United States, Europe, New Zealand, or Australia have tighter regulations and higher quality standards). Consider certified-organic meats.
  • Avoid eating liver or liver-derived products.
  • Do not eat street foods.
  • Avoid eating unusual or exotic meat products. 
  • Consider alternative protein sources.
  • Request documentation demonstrating food safety and quality standards of the meat source.


If meat consumption is unavoidable, what information should athletes collect?

If meat consumption is unavoidable, you should only consume meat products from an athlete village, your hotel, or other reputable restaurants (not street vendors or untraceable locations), and ensure the following information is obtained and recorded (on paper or as a photograph on your phone):

  1. Dates of travel
  2. Dates eaten at various establishments
  3. Name and address of establishment
  4. Menu (physical menu or picture of menu)
  5. Food diary, including type and estimated portion size of meat (photo of assembled plate showing foods consumed is also helpful)
  6. Receipt of purchase, ideally itemized, to show specifically what food was ordered

By collecting and presenting these documents, in the event of a low-level clenbuterol positive drug test, you may be able to support the evidence of an atypical finding. It is strongly recommended to abide by these recommendations to protect yourself from unintentional positive drug tests and to trace sources of contamination where exposure was unintentional. Remember that you are ultimately responsible for what goes in your body and will be held accountable accordingly.

USADA will continue to keep the sport community aware of new developments regarding this issue as they develop.



Even when a treatment is prescribed, athletes should use GlobalDRO.com to check on the anti-doping status of any procedure or medication and determine if they need an approved Therapeutic Use Exemption (TUE). For questions about specific products, substances, and methods, you can also contact USADA’s Drug Reference Line at drugreference@usada.org or call (719) 785-2000, option 2.


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