Blackhawks president and general manager Stan Bowman said in a statement on Tuesday that Toews will not report to training camp and the team will provide an update on his status when circumstances change.
In a statement, Toews says he has been consulting with doctors since experiencing fatigue during the off-season, and that it would unfair to the team if he attempted to play in his current condition.
"This offseason, I've been experiencing symptoms that have left me feeling drained and lethargic. 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.
I am grateful for the continuous support from and ongoing communication with the Blackhawks organization. Stan Bowman, Rocky Wirtz, Danny Wirtz, Jeremy Colliton and my teammates have been nothing but understanding of my situation, and I appreciate them standing by me.
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. 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."
The 32-year-old had 18 goals and 60 points in 70 games during the 2019-20 regular season for Chicago, along with five goals and nine points in the post-season. In 943 career NHL games, the Winnipeg, Man., native has 345 goals and 815 points.
The veteran forward has played 13 seasons with the Blackhawks since he was drafted third overall by the team in 2006.
The loss of Toews is another blow to the Blackhawks after the team lost centre Kirby Dach earlier this week. Dach, who was named captain of Team Canada at the world junior hockey championship, underwent surgery on Monday after fracturing his right wrist. He is expected to miss several months as he recovers.
In October, the Blackhawks published a letter to its fans that confirmed the team is in the midst of rebuilding its roster.