FILE PHOTO: Jul 19, 2015; Toronto, Ontario, CAN; Laura Zeng of the United States celebrates winning the gold medal in the rhythmic gymnastics ball final during during the 2015 Pan Am Games at Toronto Coliseum. Mandatory Credit: Eric Bolte-USA TODAY Sports/File Photo

(Reuters) - Laura Zeng, the United States top-ranked rhythmic gymnast and winner of five Pan Am Games gold medals, was handed a six-month ban on Wednesday by the United States Anti-Doping Agency (USADA).

Zeng, who also represented the United States at the 2016 Rio de Janeiro Olympics, tested positive for the banned diuretic and masking agent acetazolamide in an out-of-competition test on Oct. 18, USADA said in a statement.

Zeng provided evidence to a USADA investigation that the prohibited substance was from an altitude sickness medication, which was prescribed to her parent and given to her in response to an illness.

USADA said the 19-year-old believed she was being given ibuprofen and therefore did not have to apply for a Therapeutic Use Exemption, which is required to authorize the use of a prohibited substance in sport.

Along with her five gold medals from the 2015 Toronto Pan Am Games, Zeng also dominated the Pan American Championships staged in Lima, Peru in September, sweeping six gold medals, including the all-around title.

Zeng’s ban began on Oct. 18, the date her positive sample was collected.