How an Experimental Drug Quietly Took Over Elite Sports

A quarter-century after a lab breakthrough that thrilled its creator, a drug designed to help sick patients build muscle is better known today as one of the sporting world's most persistent headaches. In 2000, pharmacologist James Dalton was testing a new compound that would later be called ostarine, part of a class known as SARMs, or selective androgen receptor modulators, per the New York Times. The goal was to capture the muscle- and bone-building benefits of testosterone and steroids without the masculinizing side effects. Early animal studies suggested it might help cancer patients, people with osteoporosis, and frail older patients.

Instead, before it ever won approval for medical use, the drug started surfacing in human urine samples from elite athletes. Once Dalton's research was published, overseas labs began producing ostarine, and US gray-market distributors with names like Warrior Labz sold it online as a performance enhancer. The World Anti-Doping Agency banned it, but the compound spread anyway, showing up in weightlifting, track, combat sports, even horse racing. Ostarine is potent in tiny doses; tends to contaminate other supplements during manufacturing; and, researchers later found, can be transferred via sweat and maybe even sex. That has created a wave of low-level positives that anti-doping officials increasingly believe stem from accidental exposure.

The agency's zero-tolerance rules have collided with the drug's chemistry. American bobsledder Sydney Milani tested positive for a trace amount of ostarine in 2024—roughly equivalent to a drop of water in an Olympic pool, per the Times. Investigators concluded she likely ingested it unintentionally through an energy drink made by her then-boyfriend, who was using the drug, and cut her suspension from four years to one. She still missed crucial preparation for this month's Winter Games and is now eyeing 2030 instead. Similar contamination findings have cleared other athletes, including a Swiss triathlete flagged for a related SARM.

Meanwhile, ostarine itself remains in regulatory limbo. It has never been approved for human use, though a former Dalton collaborator is still pursuing it under a new name, enobosarm, as a companion to GLP-1 weight-loss drugs to preserve muscle. Dalton, now out of the drug's development loop, spends his time advising anti-doping bodies on how to detect and interpret the very substance he once hoped would be a medical advance. The Cleveland Clinic has more on why SARMs can be risky.