Starting tackle Duane Brown started Sunday's 20-6 win over Tennessee but didn't come out of the tunnel after halftime.
"Duane Brown is in the concussion protocol, seems to be feeling better today," head coach Bill O'Brien said Monday.
It is unclear when Brown suffered his concussion during the game. On Sunday, O'Brien said after talking with Brown, he felt it was "in the best interest of the team to keep him out in the second half."
Also undergoing the league's concussion protocol is safety Kurtis Drummond, who forced a fumble on Titans running back Bishop Sankey on a kickoff return in the second quarter. Drummond, who was elevated to the active roster from the practice squad last week, suffered his injury on the same play.
The Texans improved to 3-5 with Sunday's win and have bye in Week 9.