The Canadiens announced on their Twitter feed that Drouin will be placed on long-term injured reserve by the club.
"We ask everyone to respect his privacy," the Canadiens said.
Drouin has 23 points in 44 games this season. He has missed Montreal's last three games with a non-COVID related illness.
"The most important thing right now is Jo (Drouin) taking care of what he needs to take care of," Canadiens coach Dominique Ducharme said in a teleconference Wednesday. "When I heard his name this morning, I don't think hockey, I think about the person."
The Canadiens, fourth in the North Division, were scheduled to host the division-leading Toronto Maple Leafs on Wednesday.