Johnny Manziel has been placed in the CFL's concussion protocol, the Montreal Alouettes announced Wednesday.
Manziel informed the Alouettes' medical staff on Tuesday that he was feeling symptoms "that could be associated with the prescribed medication he uses for a previously diagnosed medical condition" and he missed practice to get blood work done.
The team said in a news release that Manziel was placed in the protocol because of a hit he received in its game last Saturday against Ottawa and "potential mitigating side effects of his prescribed medication."
Manziel will be "closely observed and assessed in the next few days," the team said.
The Alouettes' next game is Saturday against Edmonton.
The quarterback had a welt on his chin after last Saturday's game as a result of a big hit he took at the goal line. He fumbled on the play, but the ball was recovered by Montreal center Kristian Matte for a touchdown.
"Ran into a brick wall,'' Manziel said of the play. "That defense was fast, that defense was big and aggressive. They hit hard, they're quick. But like I told these guys, you're not going to take me out like that.''
After throwing four first-half interceptions in his Montreal debut, a 50-11 loss to Hamilton on Aug. 3, Manziel was 16-for-26 for 168 yards last Saturday without an interception in a 24-17 loss. He also ran three times for 36 yards.
The Associated Press contributed to this report.