The 33-year-old Toews got hurt during Wednesday night's 8-5 win at Detroit, but he played through the game. The center reported symptoms to the team's medical staff on Thursday.
"We're going to miss him, but we're making sure we do the right thing by this," interim coach Derek King said. "and there's no timeframe. It's when he's feeling right. You can't mess around with this stuff, so we'll just go day by day every day and see how he's feeling."
Toews has four goals and 15 assists in 43 games after he missed all of last season with what he described as chronic immune response syndrome. He also has a 58.6 faceoff win percentage.
"He's obviously our leader. He drives the bus for this team," forward Sam Lafferty said before Friday night's game against Colorado. "So we're definitely going to miss him tonight, and I think just collectively everyone's got to pull a little bit more."