Vietnam's Do Thi Ngan Thuong was expelled from the Games following a positive test for furosemide, the IOC announced Friday.
Do, who received the Wild Card invitation from the IOC Tripartite Comission, tested positive for the diurectic after competing Sunday. She finished 59th in preliminaries and did not advance to any finals.
Furosemide is a diuretic that causes water weight loss, but can also be used as a masking agent to flush other substances from the body. Russian rhythmic stars Alina Kabayeva and Irina Chaschina were stripped of their 2001 world titles after testing positive for furosemide. Other rhythmic gymnasts have also received sanctions for using furosemide, including Anna Bessonova (Ukraine) and Simona Peycheva (Bulgaria).
Arne Ljungqvist, IOC medical commission chairman, said he believed Do used furosemide inadvertently.
"My interpretation is this was probably the result of poor information given to the athlete, who did not have the knowledge of what to avoid and what she was allowed to take," Ljungqvist told the AP.
Do is the first gymnast in Olympic history who has been banned from the Games because of a positive doping test. In 2000, Romania's Andreea Raducan was stripped of her all-around gold medal because of a positive test for pseudophedrine, a banned substance at the time, that she ingested via cold medication. Raducan was allowed to compete in the individual event finals in Sydney.
Do is the third athlete of the 2008 Games to test positive for a banned substance. All expelled athletes are stripped of their Olympic credentials and required to leave the Olympic Village. Their competition results are nullified.