Coach Mike Tomlin said in a statement that team doctors are evaluating the six-time Pro Bowler.
Teammates huddled in concern as Roethlisberger fell to the turf at Latrobe Memorial Stadium. Right tackle Marcus Gilbert said Roethlisberger was rolling to the right side on a goal-line play and ran into Gilbert and linebacker Keion Adams.
Roethlisberger got up on his own accord and talked with teammates and trainers, who eventually walked him out of the stadium. He appeared to leave the premises in a car.
"It happened so fast. I saw his head whip back," Gilbert said. "I've got to see the film to see what happened. That's my guy. No one wants to see anything happen to him, especially in a practice like this, coming to work and going and not tackling."
Roethlisberger, 36, was last in the protocol in 2015 after taking a hit from then-Seattle defensive end Michael Bennett. Roethlisberger was vocal last offseason that long-term brain health would be a factor in how long he plays. Roethlisberger said this offseason that he's eyeing three to five more seasons.
Earlier in the day, Tomlin praised Roethlisberger's training camp performance. The team officially breaks camp Wednesday.
"Man, he's been awesome," Tomlin said. "Been really sharp, not only in terms of what he does, just how he's communicating and helping and aiding in the development with the people that are going to be working alongside him. It's been a very positive experience."
Prior to Roethlisberger's early exit from practice, Tomlin had ruled him out for Thursday's preseason game, along with fellow veteran Landry Jones. Rookie third-round pick Mason Rudolph and Josh Dobbs, Pittsburgh's fourth-round selection in 2017, will see all of the playing time when the Steelers visit the Green Bay Packers.
Information from The Associated Press was used in this report.