Phil Jones could be out for up to 6 weeks whilst Young is expected to be out for 3 weeks.
Ferdinand is set to only miss the next match but with United already having loads of injuries this could lead to a problem for Ferguson.
Dyer has not played a competitive game for Rangers since the opening day of the season when he was carried off on a stretcher after injuring the foot on his debut against Bolton.
He was making good progress and played during a reserve game with Tottenham this week, however, and looks likely to be out for several weeks.
QPR say he might not play until the end of the season.
The Scotland international has been suffering from ulcerative colitis, a problem with the bowel.
The statement read: “On behalf of Darren Fletcher, Manchester Unied wishes to announce that he is taking an extended break from football for health reasons.