Kenyan athlete Ruth Chepngetich, renowned for breaking the women's marathon world record, has been provisionally suspended by the Athletics Integrity Unit (AIU) after testing positive for a banned substance. The AIU revealed that Chepngetich's sample collected on 14 March contained the diuretic hydrochlorothiazide (HCTZ).

Chepngetich made headlines in October 2024 when she clinched the world record at the Chicago Marathon with an impressive time of two hours, nine minutes, and 56 seconds. However, her record-breaking performance has now come under scrutiny due to the presence of HCTZ in her system.

Hydrochlorothiazide, commonly used to treat fluid retention and hypertension, is classified as a prohibited substance at all times according to the World Anti-Doping Agency (WADA) Code. Chepngetich's urine sample showed a concentration of 3,800 nanograms per milliliter, significantly above the minimum reporting level of 20 ng/mL.

Initially, Chepngetich was not immediately suspended by the AIU upon notification of the positive test on 16 April. However, on 19 April, she chose to undergo a voluntary provisional suspension while the AIU conducted its investigation. Brett Clothier, the head of the AIU, stated that the organization had continued its inquiry and eventually issued a Notice of Charge along with the provisional suspension.

The use of HCTZ as a masking agent raises concerns about the integrity of Chepngetich's record-breaking performance, which surpassed the previous record held by Ethiopian runner Tigst Assefa by nearly two minutes. The AIU's decision to provisionally suspend Chepngetich pending further investigation marks a significant development in the case.