Olympic gold medallist Gil Roberts has been cleared of failing a drugs test, after it was found he ingested a banned substance by kissing his girlfriend.
The 28-year-old American, who won 4x400m relay gold at Rio 2016, tested positive for probenecid on 24 March.
Although Roberts was cleared at an arbitration hearing on 20 June, the details have just been released by the US Anti-Doping Agency (Usada).
An arbitrator said the athlete was “without fault”.
Probenecid is used to treat to high levels of uric acid in the blood, and can be used as a masking agent because it increases the production of urine.
After Roberts failed an out-of-competition test, he was provisionally suspended on 5 May.
He competed in the 400m at last month’s US track and field championships, qualifying for August’s World Championships in London by finishing second.
A few weeks before his failed test, Roberts’ girlfriend Alex Salazar had been taking medication for a sinus infection which contained probenecid.
Salazar took the medicine on the day of Roberts’ test and the pair kissed shortly after.
“Whenever they were together, they kissed frequently and passionately,” said the report from the American Arbitration Association.
Roberts said he did not know Salazar was taking the medicine and was unaware that kissing could lead to him ingesting any banned substance.