The Mets placed deGrom on the 10-day injured list retroactive to April 16. He could return as early as April 26 against the Milwaukee Brewers.
Mets manager Mickey Callaway told reporters the news before New York's Friday night contest against the Cardinals in St. Louis. DeGrom felt the discomfort in his throwing arm after playing catch during the team's off-day Thursday.
"He's been under the weather, his elbow is a little barking," Callaway said. "We're going to get him back to New York, have him checked out, get an MRI and go from there."
DeGrom, who previously had Tommy John surgery in 2010, was scheduled to start Saturday against the Cardinals after his original outing was pushed back due to an illness.
The 30-year-old deGrom began the season with two scoreless starts. He posted an 0-2 record with a 9.00 ERA in his last two outings and gave up five home runs over those starts, the most he has allowed in a two-game span.
The right-hander won the NL Cy Young Award last season with a 1.70 ERA in 32 starts. The Mets signed deGrom to a five-year, $137.5 million contract in March.