The Cubs placed Stewart on the 10-day injured list Tuesday with right elbow inflammation, Meghan Montemurro of the Chicago Tribune reports.
The righty's first half comes to an end after he allowed a homer, a walk and three unearned runs Monday against the Phillies. Stewart is eligible to return July 16 for the Cubs' first game after the break, but it's unclear whether he'll be ready. Elbow inflammation can often indicate a more serious injury, but there's yet to be any such word from the Cubs.