Fulchino, who had a 6.83 ERA in 29 games, has been dealing with discomfort in his elbow while throwing sliders for more than a month, and he underwent an MRI 10 days ago that showed no structural damage. He also took anti-inflammatory medication and received a cortisone shot.
"I thought I had turned the corner on this thing, and today I came in and it didn't respond," Fulchino said. "It was stiff this morning when I went to throw. It's a step in the wrong direction. We made the decision to take some time off because I've done everything I can do to get better, aside from taking time off."
After throwing a scoreless inning Monday, Fulchino tried to play catch with pitching coach Brad Arnsberg and couldn't get past 100 feet without the elbow bothering him.
"Before we went on the road trip, we talked about how he felt, and at that point he felt he was making good progress," said Astros general manager Ed Wade. "So we talked about the possibility of going on the disabled list at that point in time, and he didn't think it was necessary.
"We tried to nurse it through, and he threw well last night and felt good coming out of the game, and this morning -- not to put words in his mouth -- he felt like he was back at square one."
Wade is hopeful Fulchino will be able to return after the All-Star break.
"I wish I would have pressed the issue to put him on the disabled list at the time," Wade said. "With the All-Star break timed into this thing, that's four days right there we won't lose. Hopefully, we get him back in position to where this is a thing of the past. We know how valuable he's been to us since we claimed him off waivers."