The NBA has suspended Milwaukee Bucks forward Bobby Portis for 25 games for violating the league’s anti-drug policy, the league announced Thursday, a ban that sidelines the 2021 champion for the majority of the remainder of the season.

Portis tested positive for the drug tramadol, a medication used to treat severe pain among adults. It is an instance that his representative, Mark Bartelstein of Priority Sports, said was an accident.

“I am devastated for Bobby right now because he made an honest mistake and the ramifications of it are incredibly significant,” Bartelstein told ESPN.

“Bobby unintentionally took a pain medication called tramadol, thinking he was taking a pain medication called Toradol. Toradol is an approved pain medication that he has used previously and that teams and players use for pain and inflammation at times. Tramadol, however, is not an approved pain medication and was just recently added to the banned substance list this past spring. The tramadol pill he took came from an assistant of his, with a valid prescription for the painkiller, which he mistakenly told Bobby was Toradol. This was, again, an honest mistake that was made because of the similarity in the names of the drugs and the fact they both serve a very similar purpose. Bobby was using this anti-inflammatory pain-reducing medication to deal with an elbow injury he had this past fall and believed he was taking Toradol to alleviate some pain in preparation for that night’s game.”

Portis will not appeal the suspension, Bartelstein said.

The suspension is a devastating blow to the Bucks, who are in fifth place in the Eastern Conference at 29-24 and now lose one of the NBA’s premier sixth men. The Bucks have one open roster spot to make an immediate move while Portis will lose $2.85 million with the 25-game suspension.

Portis will be eligible to return on April 8 against the Minnesota Timberwolves — with four games left in the regular season.

Portis has averaged 13.7 points and 8.3 rebounds in 46 games, ranking sixth in scoring and second in boards off the bench among NBA players. He has finished top 3 in voting for the Sixth Man of the Year award over the past two seasons, and he has totaled the second-most points for a reserve in the past three years.