"This offseason, I've been experiencing symptoms that have left me feeling drained and lethargic," Toews said in a statement from the team. "I am working with doctors so I can better understand my condition.
"Until I can get my health back to a place where I feel I can perform at an elite level and help my team, I will not be joining the Blackhawks for training camp. I do not have a timetable for when I will rejoin the team. I am extremely disappointed, but it wouldn't be fair to myself or my teammates to attempt to play in my current condition."
Toews thanked the Blackhawks' coaching staff, front office and ownership for their understanding and then addressed the fans.
"To Blackhawks fans, I will continue to do whatever I can to get back on the ice and return to play the game I love for the team I love," he said. "I will not be making any further comment at this time and ask everyone to please respect my privacy as I focus on my health and recovery."
Toews' issue is the latest blow to a team that was already in the midst of a rebuilding project but lost two young players who were supposed to be a big part of that. Now it's also missing one of its veteran stars.
Toews has been the first-line center of three Stanley Cup-winning teams in Chicago. The 32-year-old had 60 points in 70 games last season. He has had at least 50 points in every season except one in his 13-year career and had a career-best 81 in 2019-20.
On Monday, the Blackhawks announced that 2019 No. 3 draft pick Kirby Dach will miss four to five months after breaking his wrist playing for Canada at the IIHF World Junior Championship. He underwent surgery.
Forward Alex Nylander injured his knee in the playoffs last season and underwent surgery after he felt discomfort skating before this season. He'll be out for four to six months.
Toews, along with fellow Cup holdovers Patrick Kane, Duncan Keith and Brent Seabrook, has been counted on to mentor the team's younger players. Seabrook is coming off his own health issues, however. He missed most of last season and underwent surgery on both hips and his right shoulder.
It was going to be a very different Blackhawks team even without the injuries. Cup-winning goalie Corey Crawford was not re-signed in the offseason. The Blackhawks instead are giving a chance to young goaltenders Collin Delia, Malcolm Subban and Kevin Lankinen. Also, the team traded forward Brandon Saad to the Avalanche for young defenseman Nikita Zadorov.
Chicago finished last in the Central Division last season but made the playoffs under the modified COVID-19 rules. The Blackhawks upset the Edmonton Oilers in the qualifying round, in which Toews led the team with seven points in four games. Chicago was then eliminated by the Vegas Golden Knights in five games.