The team announced that removing Molina was precautionary and because of dehydration. The game-time temperature was 90 degrees.
"I feel good," Molina said. "I got the IV. I'm feeling better."
Molina said he's never experienced anything like that before.
"I was seeing the pitcher, like three pitchers," he said. "That wasn't a good feeling. I stepped out of the box, and when I looked out at the pitcher, I was kind of dizzy. It was scary. It's the first time it's happened to me."
Molina hit a grand slam in the first inning, which was his seventh home run of the season, and added a single in the fourth, but manager Mike Matheny saw something going into Molina's third at-bat that was cause for alarm -- a flashback to a similar situation during his playing career.
"Fortunately, he was honest with us and didn't try to push through it, because that could have been bad," Matheny said. "I was looking at [Phillies catcher Carlos] Ruiz, too. He looked like he was in bad shape. I saw him bending over a lot and having trouble getting air. You have to get in shape for this kind of weather, which sounds odd. You're going to have to overhydrate, and it can sneak up on you fast."
The Cardinals catcher is hitting .325 with seven home runs and 28 RBIs.
Molina, who got the day off on Saturday, was replaced by Tony Cruz.
Nate Latsch is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.