According to the agency, Otterstrom tested positive Jan. 11 at the U.S. Snowboard Grand Prix in Breckenridge, Colo., where he won the men's superpipe. He was disqualified Wednesday.
It was the second time Otterstrom had tested positive for the stimulant methylphenadite, a drug used to control Attention Deficit Disorders (ADD) in children. Some experts consider the controversial substance stronger than cocaine.
Otterstrom failed to provide any explanation for the positive test, which may have allowed for a less severe punishment, the doping agency said.