Olympic marathon athlete banned for 10 years after positive doping test

Jackline Sakilu is among the leading group in the women's marathon at the 2024 Paris Olympics. Photo by X/Kevin Morris

According to reports, Sakilu first caught the attention of the Athletics Integrity Unit (AIU) after a urine sample taken at the Seoul Marathon in March 2025 was tested.

While the initial result was negative, a retest in September revealed the presence of banned substances. This matched a sample taken out of competition in August 2025, which detected two naturally occurring steroids: androsterone and etiocholanolone, Canadian Running Magazine reported.

These positive results suggest Sakilu may have been microdosing testosterone or related anabolic substances. By using very small doses of the hormone, an athlete can improve endurance, maintain muscle mass, and enhance high-intensity training performance while remaining under the radar of routine doping tests.

Between 2022 and 2024, Sakilu shaved nearly nine minutes off her half-marathon time and cut five minutes from her full marathon time, bringing her personal best down to 2 hours, 26 minutes and 50 seconds.

Following the 2025 discoveries, the AIU retested Sakilu's older samples from 2024. Two samples from June 29, 2024, also came back positive for androsterone and etiocholanolone.

This timeline indicates she likely participated in the Paris Olympics 2024 on Aug. 11 with banned substances in her system, entirely undetected at the time. Sakilu ultimately did not finish the 42.195 km Olympic run, withdrawing shortly after the 15 km mark.

In her defense, the Tanzanian athlete claimed her positive test was the result of illness. She stated a doctor in her hometown had prescribed medication containing ibuprofen and prednisolone.

The AIU noted that Sakilu admitted to being completely unfamiliar with the World Anti-Doping Agency's banned substance list and has never received formal anti-doping education.

Despite her explanation, Sakilu was handed one of the longest bans in AIU history. The 10-year suspension consists of two consecutive four-year bans, plus an additional two years for "aggravating circumstances."

Now 39 years old, she is barred from participating in any world athletics competitions until September 2035. All her competitive results from June 29, 2024, onward will be invalidated, though her earlier half-marathon record of 66 minutes and 5 seconds and her early 2024 Chongqing Marathon victory will stand.