Jackson is 5-11 with an ERA of 5.68 and 104 strikeouts in 115.2 innings this season. On Thursday night, he allowed five runs, on seven hits over five innings. After Jackson was removed from the game, it was announced that the pitcher had to leave because of cramping in his right hand.
Jackson, 30, is due around $26 million through the 2016 season.
The Cubs are 41-59 going into Friday, and sit 15.5 games back of the NL Central-leading Milwaukee Brewers. They have already traded pitchers Jeff Samardzija and Jason Hammel to Oakland. Teams reportedly have expressed interest in shortstop Starlin Castro, but the Cubs don't plan to trade him "this month."
- Sarah Barshop