Phillips recorded the out but said he felt dizzy after Ramirez's arm struck him in the temple.
"I just felt kind of light after that, and I started seeing stars and stuff," Phillips said. "I started feeling like I was off balance a little bit."
In the bottom of the third, Phillips managed to rope an RBI single to right field for the Reds' first run.
"I was blinking my butt off. I don't know how I hit that ball, honestly," Phillips said. "I was up there just swinging the bat, especially that first pitch. He threw me a curveball or something. I didn't even see the ball. The next thing you know, he threw me a fastball in and I got it over there. I was happy, but I was running to first and I almost fell. I don't think a lot of people noticed that."
Phillips lasted two more innings before Reds manager Dusty Baker replaced him with Miguel Cairo in the top of the sixth.
"He just said he was feeling dizzy," Baker said. "Nowadays, when a guy says he's feeling dizzy, you have to take every precaution and get him out of there. That's what we did."
Phillips said he felt like he was going to throw up and had the medical staff examine him in the clubhouse after he left the game.
"They had me in there doing some simple things, just seeing about my balance and seeing if I had a concussion or something like that," he said. "I was just in there doing what they told me to do. I really don't know what was going on. To tell you the truth, I can't remember what they were saying. I wasn't all the way there, so I wasn't really paying attention to everything they were saying."
Phillips was 1-for-2 at the plate before leaving the game.
The Reds could use Phillips' bat as they head into an 11-game road stretch before the All-Star break. He is also second among NL second basemen in All-Star balloting, which ends Thursday night at 11:59 p.m. ET.
Phillips, who is hitting .316 with five homers and 21 RBIs in June, said he was unsure when he would return to the lineup.
"I think I'm all right," Phillips said. "I feel like I'm not all the way there right now. I still feel like I'm kind of off, but I think I'll be all right. I'm going to try to go out there and play, but if I'm feeling like I'm feeling right now, then I'm not going to go out there and just try to play. I'm going to try my best."
This season, Phillips is hitting .289, with 10 home runs and 46 RBIs. Cairo and infielder Wilson Valdez are the two possible options to replace Phillips if he is out for an extended period of time.
Cairo is hitting .135, with three RBIs, playing primarily at third. Valdez is batting .237, with nine RBIs and has played in eight games at second base.
Mark Clements is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.