The Athletics Integrity Unit has slapped Mexican sprinter Yamile Herrera with a three-year suspension for her positive test for Oxandrolone, an anabolic androgenic steroid, at the 2026 World Athletics Relays in Gaborone, Botswana. The decision was issued on June 19, 2026, and the sanction will be in effect from June 3, 2026, until June 2, 2029. This has an impact not only on Herrera but also on others.

Mexico’s 4x100m Mixed Relay Team, which included Brandon Heredia, Gerardo Lomeli Ponce, and Alejandra Urias, has been disqualified from all results at the World Athletics Relays dating from May 2, 2026, with all titles, medals, prizes, and prize money forfeited. It was the date when Herra, 26, gave a urine sample in Gaborone. 

The event had taken the world by storm as Jamaica had broken the mixed 4x100m world record twice in two days, with the final run taking 39.62. Mexico, which took on Heat 3 with Jamaica, Australia, and Great Britain, recorded 41.57 in the qualifying rounds, which the Mexican athletics community said was one of the country’s best performances at the event. That time and those results have now been wiped from the record books.

On May 20, 2026, a WADA-accredited laboratory in Paris reported an Adverse Analytical Finding from Herrera’s sample, confirming the presence of Oxandrolone and its metabolites. The AIU notified Herrera on June 3 and gave her until June 10 to respond. She admitted the violations on that deadline, signing a formal Admission of Anti-Doping Rule Violations and Acceptance of Consequences. 

That decision entitled her to a one-year reduction from the standard four-year ban that applies to a first-time violation involving a non-specified substance. The four-year default period was shortened to three years. And she has waived her right to a disciplinary tribunal hearing. 

Oxandrolone, also known commercially as Anavar, was developed for medical use in the treatment of osteoporosis, a condition that can result in bone pain and severe weight loss. In sport, it falls under the category of S1.1 Anabolic Androgenic Steroids on the WADA Prohibited List, meaning it is prohibited at all times, both in and out of competition. It is especially common among female athletes who are being doped and among athletes seeking less aggressive types of steroids, as it promotes muscle growth more anabolically than androgenically and is associated with fewer hormonal side effects.

According to anti-doping databases, Oxandrolone has been responsible for bans across 390 athletes globally, with 41 of those cases in athletics specifically. Russia accounts for the largest number of cases among nations.

A breakthrough season ends in a three-year suspension  

This infraction comes in the middle of a particularly impressive uptick in Yamile Herrera’s personal game in 2026. After a difficult 2025 campaign, where she finished fifth in both the 100m and 200m at the Mexican National Championships, Herrera had clocked personal-best times. In April 2026, she set her personal records with 11.55 in the 100m and 23.60 in the 200m, mere weeks before the World Relays.

Those times, which are now marked as illegal on her World Athletics profile, were recorded in the weeks before her sample was taken. She has not competed since May 6, 2026, when she was notably absent from Mexico’s National First Division Championships roster.

The disqualification of the relay team’s results has wider consequences for Mexico’s athletics program. The squad that competed in Gaborone included Brandon Heredia, a seven-time national champion; Gerardo Lomeli Ponce, the reigning national champion in the 100m and 200m; and Alejandra Urias, Mexico’s U20 national champion in both events. None of those athletes is involved in the doping case.

However, under World Athletics rules, if a relay team member commits a doping violation, the entire team’s results are canceled unless the case falls under specific fault or negligence exceptions. The implications of disqualification for the Beijing 2027 World Athletics Championships will now have to be evaluated by the relevant governing bodies. 

WADA and Mexico’s Comité Nacional Antidopaje have the right to appeal the decision to the Court of Arbitration for Sport in Lausanne within 15 days of receiving the full case file. Herrera also has the right to cross-appeal if either body chooses to do so. For now, she has yet to make a public statement, leaving the future of the case uncertain.