American Merritt tested positive for testosterone prohormones
Olympic and world 400m champion LaShawn Merritt has been suspended for nearly two years for doping.
The 24-year-old American tested positive for testosterone three times between October 2009 and January 2010.
But with the 21-month ban running from 28 October 2009 - when he first tested positive - he will be eligible for the 2011 World Championships next August.
Merritt, who won the 400m Olympic title in Beijing, accepted a provisional suspension earlier this year.
"As a result of the arbitration decision, Merritt received a 21-month period of ineligibility, which began October 28, 2009, the day the first sample was collected," said
the US Anti-Doping Agency (Usada) in a statement.
"Merritt has also been disqualified from all competitive results achieved at and subsequent to October 28, 2009, including forfeiture of any medals, points, and prizes."
The American, who also clinched the world 400m title in Berlin last year, had admitted using an over-the-counter male enhancement product containing DHEA (dehydroepiandrosterone) and pregnenolone.
He claimed in April he had not been aware that the product he used contained the banned steroid and admitted he had made a "foolish, immature and egotistical mistake".
He said in a statement at the time: "To know I have tested positive as a result of a product I used for personal reasons is extremely difficult."
Merritt cooperated with doping authorities and arbitrators took three months off the normal two-year ban for first-time offenders.
ruling by the three-man American Arbitration Association (AAA)
read: "He wasn't training so he wasn't thinking about track.
"His mindset when purchasing the product was thinking about having sex with a woman. It never entered his mind that the product contained a steroid derivative. He admitted he did not look at the label."
Merritt was reportedly devastated when he found out what had caused his positive tests.
The ruling added: "He testified that his heart sank. He thought how stupid he had been. Rather than hiding his fact Mr Merritt announced it to the world, recognising the humiliation that would soon follow, and immediately informed Usada."