The International Tennis Integrity Agency (ITIA) today confirms that Guatemalan tennis player Juan Sebastián Domínguez Collado is free to return to play, having provided evidence to satisfy the ITIA that their positive test for the prohibited substance clostebol came as a result of close contact with a family member using clostebol products to treat a medical condition.
In the days leading up to Domínguez Collado’s doping control test, the player was sharing living quarters with his father, who, on the advice of his physician, had been conservatively treating a condition with two separate clostebol-based products, multiple times a day.
Domínguez Collado asserted that he and his father had regular physical contact and shared access to a mobile device. In addition, the player shared communal towels with his father, who stated that he had regularly used the towels to wipe his hands after applying the products to his body, as an alternative to washing after each application, further increasing the exposure to the clostebol residue.
As part of the investigation, the ITIA sought scientific advice from the WADA-accredited laboratory in Montreal, Canada, where the sample was analysed, for expert views on the plausibility of the player’s explanation. Upon review, the laboratory confirmed that the player’s explanation was plausible based on the low level of clostebol in the player’s sample, and, having taken all evidence into account, the ITIA determined that the player’s explanation was more likely than not the source of the clostebol.
Following precedent in similar recent cases from tennis and other World Anti-Doping Code-compliant sports, the ITIA issued a decision of No Fault or Negligence on 2 February 2026. Domínguez Collado is free to return to play.
The player, who reached a career-high world singles ranking of 1660 in October 2025, provided an in-competition sample while competing in an ITF World Tennis Tour event in Kayseri, Turkey, on 2 October 2025.
The sample was split into A and B samples and the subsequent analysis found that both samples contained a metabolite of clostebol, which is prohibited under the TADP, in the category of Anabolic Androgenic Steroids (Section S1.1 of the 2025 World Anti-Doping Agency Prohibited List).
Clostebol is a non-Specified substance, and Domínguez Collado did not possess a valid TUE for the substance.
Findings for non-Specified Substances carry a mandatory provisional suspension – in Domínguez Collado’s case, this has been in effect from 19 November 2025. Players have the right to appeal the imposition of their provisional suspension before an independent tribunal chair. Domínguez Collado did not appeal.
The ITIA is an independent body established by its tennis members to promote, encourage, enhance, and safeguard the integrity of their professional tennis events.
To read the decision in full, click here.
Ends
Published 10 February 2026 14:00
