On 9/9, the Athletics Integrity Unit (AIU) announced that Chepngeno tested positive for triamcinolone acetonide, an anti-inflammatory corticosteroid on the World Anti-Doping Agency (WADA)'s prohibited list.

The sample was collected immediately after Chepngeno's victory at Sierre-Zinal on 9/8 and analyzed at the WADA laboratory in Cologne, Germany.

Joyline Chepngeno competing at the 2025 Sierre-Zinal race in Switzerland. Photo: Keystone

Joyline Chepngeno competing at the 2025 Sierre-Zinal race in Switzerland. Photo: Keystone

Chepngeno accepted the violation and will be banned until 8/9/2027. Sponsor Salomon immediately terminated their contract with the runner, stating, "This behavior completely contradicts Salomon’s core values. We do not tolerate any violation of these principles.".

The scandal has also led to a ban for Chepngeno's coach, Julien Lyon, and the Milimani Runners team, from participating in Sierre-Zinal until further notice. Lyon must reimburse all accommodation, travel, and administrative expenses paid by the organizers and compensate for damage to the event's reputation.

Chepngeno had recently made a splash in the trail running world with victories at Sierre-Zinal on 9/8 and UTMB Mont Blanc OCC on 28/8. She made history as the first Kenyan athlete to win the 50 km OCC race at UTMB Mont Blanc. This achievement placed Chepngeno among the brightest stars of mountain running and sparked hope for a wave of Kenyan athletes, well-known in track and field but relatively new to trail running.

Sierre-Zinal and UTMB are considered the "Tour de France" and "Wimbledon" of trail running. Sierre-Zinal, which began in 1974, is a classic mountain race that any runner would want to experience, known for its spectacular course in the Swiss Alps. UTMB is the world's most prestigious ultramarathon, taking place around the Alps and attracting a large number of athletes and media.

However, the positive doping test voids Chepngeno's results in both races. The UTMB organizers awarded the women's OCC title to Miao Yao (China), while the Sierre-Zinal title went to Caroline Kimutai (Kenya).

Joyline Chepngeno made history as the first Kenyan athlete to win the 50 km OCC race at the 2025 UTMB Mont Blanc. Photo: Carreraspormontana

Joyline Chepngeno made history as the first Kenyan athlete to win the 50 km OCC race at the 2025 UTMB Mont Blanc. Photo: Carreraspormontana

This is not the first time Sierre-Zinal has seen its women's champion lose the title due to doping. In 2022, Esther Chesang, also from Kenya, had her results annulled for testing positive for the same substance, triamcinolone acetonide. These incidents raise questions about doping control in trail running, a sport associated with endurance, integrity, and harmony with nature.

The incident also fuels concerns about doping in Kenyan long-distance running. In July, the marathon world was shocked by the news that women's record holder Ruth Chepngetich was provisionally suspended for testing positive for hydrochlorothiazide (HTCZ), a banned diuretic often used to mask performance-enhancing drugs (PEDs).

Hong Duy (via Canadian Running Magazine)