Manager Jerry Manuel said Wednesday that the team plans on scaling back Pelfrey's workload and will make a decision on Sunday's start later in the week.
"It's something that we are trying to handle and deal with, and we have to be somewhat cautious because of what he obviously means to this rotation," Manuel said. "We consider him the No. 2 guy. So we have to make sure we take care of this and take care of him."
Pelfrey has walked six batters in his first two starts of the season, allowing nine earned runs in 10 innings en route to an 8.10 ERA.
Manuel said the team approached Pelfrey to get his arm checked out following his performance Monday, in which he was relieved after allowing five earned runs and eight hits in five innings.
Despite throwing a career-high 200 2/3 innings last season, Pelfrey said he wasn't overly concerned when he initially started experiencing soreness last month.
"Every year, I probably get some form of tendinitis," he said. "This is not a big deal ... right now, the plan is to start on Sunday."
Pelfrey started taking anti-inflammatory medication on Wednesday and will combine rest with ice in the hopes of being 100 percent in "a few weeks."
But given that the season is young, the Mets may be more inclined to proceed with caution.
"We are going to see how that [rest and ice] affects him in the next couple days," Manuel said. "We will probably get together and determine whether or not his start is in jeopardy. Right now we have not made that decision on him."
If Pelfrey does not make his scheduled Sunday start, Manuel said the team will use a pitcher in their Minor League system and not shift around the bullpen.
Regardless of whether he starts, Pelfrey does not want to use the tendinitis as an excuse for his lackluster performance.
"I haven't pitched well, but I'm not saying this forearm tendinitis is the reason for that," he said. "I should be better. I should be pitching better than I am."
Brittany Ghiroli is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.