"Everybody I've talked to that's had it says it gets worse for a couple days but then day three, I should be feeling the best I've felt in a while," Carpenter said. "Hopefully that's the case."
Carpenter, 31, acknowledged that he's been battling shoulder soreness for much of the season, but the pain intensified in recent weeks. It reached a point on Monday where manager Mike Matheny felt it necessary to pull Carpenter out of the game.
That's when the club decided it would have doctors take a closer look at the shoulder. Cardinals head physician George Paletta read the scan, as did a consulting doctor in San Diego. Both agreed that giving Carpenter a cortisone shot would be the right course of action.
Surgery was not considered, Carpenter said.
"Nothing so major that he's not going to be able to see some benefits here with some rest and a little bit of treatment and then get him on anti-inflammatories," manager Mike Matheny added.
Perhaps the persistent shoulder discomfort explains some of the trouble Carpenter has had gaining offensive traction this year. Though he's maintained an on-base percentage (.374) near his career-average, Carpenter has a career-worst .239 batting average and is coming out of a month in which he hit .202.
Carpenter went 2-for-17 on this road trip.
"One thing I'll never do is be a guy who makes excuses, but the shoulder has been something that has been lingering for most of the season," Carpenter said. "It makes it hard when you know you're in a situation where you know you can play [but] is my 60 percent worth it? Hopefully here in the next day or two, we can get that 60 back to 100. That's the goal."
Jenifer Langosch has covered the Cardinals for MLB.com since 2012, and previously covered the Pirates from 2007-11. Follow her on Twitter and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.