St. Louis Cardinals veteran right-handed pitcher Adam Wainwright, who has been dealing with shoulder discomfort, is headed to the injured list, manager Oliver Marmol said on Tuesday.

In the 15-2 loss to the host Miami Marlins, Wainwright (3-4, 7.66 ERA) had his third consecutive outing of less than four innings. He was lifted after consecutive one-out walks in the fourth. The 41-year-old gave up seven runs, four earned, and seven hits.

Wainwright, who is in his 18th season with St. Louis, is set to retire at the end of this season.

"There's not a whole lot behind him at the moment," Marmol said. "This is a guy who's meant a lot to this organization. We're going to take a deeper look at this and he's determined to finish well."

During Wainwright's difficult three-game stretch, he has allowed 20 runs and 24 hits. The Cardinals have been outscored 29-2 in Wainwright's past two starts.

"It's stuff that I thought I could get through," Wainwright said. "I don't want to use it as an excuse. The results are not where I wanted to be. It's not fair to the team to keep doing that three times in a row with no chance to win. I don't want the story to be that every time that I pitch."

The Associated Press contributed to this report.