Wood, who ranks among the National League leaders with 24 saves in 29 opportunities, has been bothered by the blister for three weeks. He was not available Saturday in the Cubs' 11-inning, 8-7 win over the San Francisco Giants.
"We didn't have Woody today," Cubs manager Lou Piniella said. "Woody's got a blister, and he's not going to pitch at all until after the break. He wasn't available. He can't pitch tomorrow and he probably won't be able to pitch in the All-Star Game."
Wood, named to the All-Star team in 2003 but as a starter, has battled back from shoulder problems which limited him to 14 starts from 2005-07 to pitch again this season.
"[The blister] would allow me [to pitch]," Wood said, "but it's not the smartest decision. We have the opportunity to take six days to let it get better and not deal with it the rest of the year.
"My main focus is being able to help this team the second half, and I think this is the smartest decision," he said.
The Cubs have the best record in the National League heading into the break.
"It's a little bit disappointing," Wood said. "I've been through a lot to get to this point, and was rewarded to make the All-Star team, and now I'm not going to be able to pitch an inning. I think it's the right decision."
Wood was one of seven Cubs to be named to the National League All-Star team, but now is the second who will not be able to participate. Alfonso Soriano, voted to the starting outfield, also cannot play because he's rehabbing from a broken bone in his left hand, suffered June 11.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.