Clostebol case resolved after ITIA accepts indirect exposure explanation

Juan Sebastián Domínguez Collado has been cleared of an anti-doping violation involving clostebol, the same prohibited anabolic steroid that featured in Jannik Sinner’s high-profile case in 2024. The International Tennis Integrity Agency (ITIA) ruled that the 23-year-old Guatemalan player’s positive test resulted from inadvertent external contamination, overturning a provisional suspension imposed after an in-competition control at an ITF World Tennis Tour event in Turkey.

Clostebol drew widespread attention in tennis last year after Sinner tested positive twice at Indian Wells, eventually accepting a three-month suspension following a World Anti-Doping Agency appeal. Domínguez Collado’s case also involved trace levels of the substance, but the ITIA concluded that it entered his system through indirect contact rather than ingestion, a distinction that proved decisive in the final ruling.

The sample was collected on October 2, 2025, during the ITF World Tennis Tour M15 tournament in Kayseri. At the time, Domínguez Collado had recently reached a career-high ATP ranking of World No. 1660. Analysis of the A sample detected a clostebol metabolite, and subsequent testing of the B sample confirmed the finding, formally establishing the presence of the prohibited substance.

Because clostebol is classified as a non-specified substance under the World Anti-Doping Agency Prohibited List, and because Domínguez Collado did not hold a valid Therapeutic Use Exemption, the ITIA imposed a mandatory provisional suspension on November 19, 2025. A pre-charge notice issued the same day alleged violations of Articles 2.1 and 2.2 of the Tennis Anti-Doping Programme, relating to the presence and use of a prohibited substance.

As a result of the suspension, Domínguez Collado was barred from all professional tennis activity, including competition, training, coaching, and attendance at events sanctioned by ITIA member organisations. These restrictions applied across the ATP, WTA, ITF, the four Grand Slam tournaments, and all affiliated national federations. Although he had the right to challenge the provisional suspension before an independent tribunal chair, he did not exercise that option.

During the investigation, Domínguez Collado submitted evidence identifying an unusual source of contamination. The ITIA confirmed that, in the days leading up to the doping control, the player had been sharing living quarters with his father, who had been applying two clostebol-based medications on medical advice multiple times per day.

“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.”

The player reported regular physical contact with his father and the shared use of personal items. According to the ITIA, communal towels were used by both individuals, with the father frequently wiping his hands on them after applying the medication rather than washing after each application, increasing the likelihood of residue transfer.

“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.”

To assess the plausibility of this explanation, the ITIA sought expert input from the WADA-accredited laboratory in Montreal, Canada, where the samples were analysed. The laboratory concluded that the low concentration of clostebol detected in Domínguez Collado’s samples was consistent with indirect exposure rather than deliberate use. “Upon review, the laboratory confirmed that the player’s explanation was plausible based on the low level of clostebol in the player’s sample.”

After reviewing all evidence, the ITIA determined that Domínguez Collado had established the source of the prohibited substance on the balance of probabilities and issued a finding of no fault or negligence, lifting the provisional suspension with immediate effect. “Having taken all evidence into account, the ITIA determined that the player’s explanation was more likely than not the source of the clostebol.”

While comparisons with the Sinner case were inevitable, the ITIA stressed that Domínguez Collado’s clearance was based strictly on the specific facts and scientific evidence presented. Findings of no fault or negligence remain rare, and the agency said the decision does not signal a broader change in anti-doping enforcement. Domínguez Collado is now free to resume his professional career.