The Habs' position in the standings has also changed since Drouin went down.
On November 15, Claude Julien's contingent sat second in the Atlantic Division with 25 points courtesy of an 11-5-3 record. Now, they find themselves 10 points back of the final playoff spot.
Drouin stressed that he would've liked to help his teammates right the ship a lot earlier.
"It's frustrating. I couldn't help my team for eight weeks. We need points and we're fighting with other teams for a playoff spot. Every game I watched was harder and harder for me," said Drouin. "It's tough, but it's part of hockey. It was disappointing that I couldn't help my team."
More good news for Gallagher
Like Drouin, forward Brendan Gallagher took part in Tuesday's practice with the rest of the group.
He was also sporting a regular practice jersey.
Gallagher has missed the last six games with headaches.
The 27-year-old Edmonton native indicated that his status improved dramatically in recent days.
"I've been headache-free since some point during the bye week, so it's been a little while now. The headaches were there for a few days, and then after a couple of days it would come and go, come and go," explained Gallagher, who has 15 goals and 32 points in 41 games this season. "But, they've been gone for good since early in the bye week."