Stanton was hit in the back of the helmet during a Miami Marlins intrasquad game by a fastball that got away from Fernandez, the team's top pitching prospect. Stanton remained on his feet but left the game and said the beaning affected his eyesight.
"I wasn't dizzy," he said. "I saw a little grayness and fuzziness on the outside of my eyes, but it's subsiding now."
Stanton said he didn't expect to miss any playing time, but further medical evaluation was planned.
The 20-year-old Fernandez, the Marlins' first-round amateur draft pick in 2011, said the pitch slipped from his hand but still had plenty of velocity.
"Over 95 mph, I know it was. It's a scary moment," the right-hander said. "My hands were sweating a lot. It was just not a good pitch. I feel bad. It's not a good feeling, I promise you."
Fernandez followed Stanton into the clubhouse to apologize.
"When I asked him how he was doing, he laughed," Fernandez said. "I told him I was sorry. He said, 'Bro, it's OK. It's baseball. It happens.'"
The pitch, the first from Fernandez to Stanton, struck the slugger on the lower edge of the helmet above his neck. Stanton led the NL in slugging percentage last year and hit 37 home runs.
Fernandez is expected to start the season with Double-A Jacksonville and is considered a candidate to break into the majors this summer.