Reilly sustained a helmet-to-helmet hit in the first quarter of Saturday's 34-22 loss at home to the Toronto Argonauts and was evaluated before staying in the game for one more play.
He completed a touchdown pass to Shamawd Chambers, but returned to the sideline right after experiencing symptoms of a concussion. At that point he was removed from the game and examined by the team physicians for a second time.
Reilly will continue to be evaluated and will follow a standardized return-to-play protocol.
The 28-year-old finished the game making six of 10 pass for 80 yards, one touchdown and one interception. He rushed once for nine yards.