At a news conference, team physician Dr. David Mulder told reporters Theodore uses Propecia, a hair restoration product. It is banned by the World Anti-Doping Agency.
Mulder said Propecia is not an anabolic steroid, but acts as a masking agent.
"He's been taking it on the advice of a dermatologist," Mulder said, adding that Theodore has been using the product for eight years. "He has had very good success and he feels it has helped hair growth and prevented further loss, and he has taken it with my knowledge."
Mulder said Propecia is not performance-enhancing and will remain in a person's system for over 30 days. For now, the 30-year-old Theodore is not expected to receive any disciplinary action from the NHL.
The NHL and the NHL Players' Association implemented a new drug testing program as part of the new collective bargaining agreement last year that ended the league's lockout of players.