During a radio interview with 105.7 The Fan on Wednesday night, the former NFL Defensive Player of the Year acknowledged that the injury may be having a negative effect on his play.
Reed's tackling wasn't sharp during the Ravens' 31-29 win over the Dallas Cowboys.
Reed isn't listed on the Ravens' injury report.
Reed didn't indicate when the shoulder injury occurred or which shoulder is bothering him.
Tackling could continue to be an issue for Reed, as it was late last season when a nerve impingement in his neck and a shoulder injury flared up.
Reed delivered some punishing hits in a win over the New England Patriots earlier this season, but hasn't had anywhere near as impactful tackles since that game.