Williams’ return to Queen’s Club intensifies scrutiny over GLP-1 monitoring

Serena Williams returned to professional tennis at the Queen’s Club in London, partnering with Canadian teenager Victoria Mboko to defeat the No. 3 seeds, Erin Routliffe and Nicole Melichar-Martinez, in women’s doubles. The straight-sets victory marks the 44-year-old’s first competitive match in nearly three years and serves as a preparation for Wimbledon, where she is a seven-time champion. While Williams has not yet committed to playing singles, her return has immediately placed her at the centre of a broader debate regarding the use of GLP-1 receptor agonists, such as Zepbound, in elite sport.

Williams disclosed her use of Zepbound, a drug designed to treat diabetes and aid weight loss, through Ro, a telehealth company where she serves as a paid ambassador. Her husband, Alexis Ohanian, is a major investor in the firm. Speaking on Oprah Winfrey’s podcast, Williams stated that training alone was insufficient to manage her post-pregnancy weight and that the medication helped alleviate joint pain. She described the decision not as taking a shortcut, but as addressing a biological issue that hindered her career longevity.

The World Anti-Doping Agency (WADA) has included semaglutide and tirzepatide, the main classes of GLP-1 drugs, in its monitoring program since 2024. This status tracks usage patterns in and out of competition but does not prohibit the substances. WADA is currently evaluating whether these drugs violate the “spirit of sport” or enhance performance, with no timetable set for a decision on banning them. The International Tennis Integrity Agency (ITIA) manages tennis anti-doping protocol, but WADA oversees compliance for Olympic sports.

Manufacturers of these drugs have responded to the regulatory landscape differently. Novo Nordisk expressed support for WADA’s monitoring but discouraged use outside approved indications. Eli Lilly did not comment. Matthew Fedoruk, chief science officer at the USADA, warned that future iterations of GLP-1 drugs may be tweaked to minimise muscle loss, potentially increasing their appeal and risk as performance-enhancing substances. He described this as a growing threat requiring close monitoring.

Williams’ path to the Queen’s Club involved navigating strict eligibility requirements. Her name appeared in the tennis anti-doping testing pool last year, a prerequisite for return that requires athletes to be available for daily location reporting and random testing. After initially denying plans for a comeback in December 2024, Williams confirmed her participation shortly before the tournament. Her return highlights the complex intersection of medical treatment, athletic performance, and evolving anti-doping governance.