He'll be on antibiotics for four more days.
"I finally woke up this morning feeling somewhat normal and able to start to eat solid foods again, which is nice," said Gray, who only lost a couple of pounds in the process. "I'm just really glad to be back here, for sure."
Though Gray is looking healthy again, the A's will likely skip him a second time through the rotation to ensure him plenty of rest. A's manager Bob Melvin said there's a "good chance" Chris Bassitt makes another start, against the Mariners on Sunday.
"Once we determine how he's feeling, then we'll get him off a mound and see where we go from here, but no determination on a day to pitch yet," Melvin said.
Bassitt allowed the Rockies one run in five innings on three days' rest in place of Gray on Tuesday, greatly impressing Gray, who watched from his hospital bed. Gray told him as much in a text message after the game.
Essentially quarantined for the majority of his stay at John Muir Medical Center in Walnut Creek, Calif., Gray found solace in watching his teammates.
"I'd be lying there all day long and just couldn't wait for the games to come on," he said. "It was something I could do."
A's head trainer Nick Paparesta confirmed that no one else had been infected by the foodborne illness, which "we feel that he most likely did not get it at our facility," he said.
"We're going to do everything we can internally to investigate that and verify that that wasn't the case," added Paparesta. "[Gray] did eat at two venues away from our facility, on Thursday night and Friday before he came to the ballpark. That would be a possibility as well."
Despite potentially missing a second start, Gray remains a strong All-Star candidate, with nine wins and a 2.09 ERA, which ranks second in the American League.
• The A's on Thursday acquired right-hander Cody Martin from Atlanta for international bonus slot 53 and assigned him to Triple-A Nashville. To clear a spot on the 40-man roster, the A's designated infielder Nate Freiman for assignment.
Martin was on the Braves' Opening Day roster and went 2-3 with a 5.40 ERA in 21 relief appearances over two stints with Atlanta in his Major League debut.
• Switch-pitcher Pat Venditte (strained right shoulder) is playing catch with both arms out to 90 feet. The A's hope to have him throwing off the mound again during the All-Star break.