American middle-distance runner Jonah Koech has been banned from competition for three years after showing abnormal blood markers consistent with doping. The 29-year-old's 2025 breakthrough victory at the US Outdoor Championships—where he set a meet record and defeated an Olympic gold medallist—has been invalidated. Detection occurred through the athlete biological passport system, which monitors blood values over time to identify doping without requiring a positive chemical test. Koech accepted the ban after USADA's findings.

All of Koech's competitive results from late July 2025 onwards have been expunged, including medals and prizes. Since his championship win, the Kenya-born runner competed only once, finishing 13th at the World Championships in Tokyo before the doping case emerged. Koech became eligible to represent the United States in 2021 after competing for American universities from 2015 to 2019.