Backstrom missed Team Sweden's 3-0 loss to Canada in Sunday's gold medal game in Sochi, Russia, after Olympics officials said he tested positive for a banned substance.
Swedish sports officials said the positive test was due to routine allergy medicine, and the NHL said Sunday the substance is not on the league's banned list.
Deputy Commissioner Bill Daly said the test result "was the result of a common allergy medication taken by the player knowingly, with the approval of the team doctor and without the intention of gaining an illegal or improper performance-enhancing benefit."
Thus, he added, "we do not anticipate there being any consequences relative to Nicklas' eligibility to participate in games for the Washington Capitals."
The Caps resume their NHL schedule Thursday against Florida.