The Bears said Young suffered a triceps injury in Week 4 against Green Bay, but he was listed as having limited participation in practice last Thursday. Young, who subsequently missed the next two days of practice and was listed as doubtful, was inactive for Monday's 20-17 loss to Minnesota.
Young had 7 tackles, 2 sacks and 4 quarterback hurries in the first 4 games for the Bears this season.
An eight-year veteran, Young has been one of Chicago's best pass-rushers since he joined the club in 2014. Young set a career high with 10 sacks in his first year in Chicago, and he signed an extension in the summer of 2016 after he switched from defensive end to outside linebacker to fit in the 3-4 defense used by veteran coordinator Vic Fangio.
Young, who is signed through 2018, is the fifth Bears starter to land on injured reserve. He joins wide receivers Cameron Meredith and Kevin White, safety Quintin Demps and inside linebacker Jerrell Freeman.
The Bears used a rotation of Leonard Floyd, Pernell McPhee and Sam Acho at outside linebacker in Week 5. Another veteran outside linebacker, Lamarr Houston, was recently released off injured reserve after he got hurt in the final preseason game.