Dunning is being evaluated by the team's medical staff, and the extent of the issue is currently unknown.
Dunning, 24, is ranked as the No. 80 prospect in baseball by MLB Pipeline and the No. 6 prospect in the White Sox's system. He had a 2.71 ERA and 1.19 WHIP in 86 1/3 innings split between advanced Class-A and Double-A in 2018.