Kosta Karageorge, 22, a senior, was last seen at his apartment in Columbus around 2 a.m. Wednesday, according to a police report.
His mother, Susan, told authorities he has suffered several concussions and has had spells of being extremely confused, the report said. His sister Sophia Karageorge told the Columbus Dispatch newspaper her brother suffered his latest concussion a month ago and might have become disoriented.
The Columbus Police Department said it was treating his disappearance as a missing persons case and does not suspect foul play.
Karageorge, who plays defensive tackle, was absent Saturday from Ohio State’s last regular season game against Michigan, which the team won 42-28.
He was set to be among 24 seniors honored on the field before the game began, team officials said, and an enormous version of his missing person’s flier was displayed above the stadium’s scoreboard during the match.
“He is a young man who joined the football team in August and was a hard worker on the field and pleasant off the field,” football coach Urban Meyer said in a statement.
“Our thoughts continue to be with the family of Kosta Karageorge and we pray that he is safe and that he is found soon.”
Hundreds of volunteers have posted fliers and were helping search the area for Karageorge, who stands 6 feet 5 inches (1.9 meters) tall and weighs 285 lbs (129 kg), school officials and local law enforcement said.
His teammates also posted on Twitter that they were offering a $1,000 reward for information leading to his whereabouts.