Ruth Chepngetich, the women's marathon world record holder, has been provisionally suspended by the Athletics Integrity Unit (AIU) for a banned substance.

The diuretic hydrochlorothiazide (HCTZ) was detected in a sample collected from Kenyan Chepngetich on 14 March, the AIU said in a statement. Chepngetich, 30, broke the world record to win the Chicago Marathon in October 2024, clocking a time of two hours, nine minutes and 56 seconds.

HCTZ is used clinically to treat fluid retention and hypertension and is a prohibited at all times under the World Anti Doping Agency (WADA) Code. Chepngetich's time in Chicago surpassed Ethiopian Tigst Assefa's previous record set at the 2023 Berlin Marathon by nearly two minutes.

Used commonly as a masking agent, HCTZ has a minimum reporting level of 20 nanograms per millilitre (ng/mL) in urine. Chepngetich's sample showed 3,800 ng/mL.

Chepngetich was not provisionally suspended by the AIU at the time of notification on 16 April. However, on 19 April, she opted for a voluntary provisional suspension while the AIU's investigation was ongoing.

"In the intervening months, the AIU continued its investigation and today issued a Notice of Charge and imposed its own provisional suspension," AIU head Brett Clothier said.

Chepngetich stunned the world when she ran 2hr 9min 56sec at the Chicago marathon last October, a time that shattered the previous record by almost two minutes.

The 30-year-old, however, withdrew from the London Marathon in April where she was due to be the star attraction, saying at the time she was “not in the right place mentally or physically” to race her best.