Clowney, the No. 1 pick in the 2014 NFL draft, missed Houston's final two preseason games due to an undisclosed injury. He was not listed on the team's Week 1 injury report.
In June, the rookie had sports hernia surgery, which he was still recovering from at the start of camp.
In three seasons at South Carolina, Clowney had 24 sacks and 47 tackles for loss.
The Texans open the season at home versus the Redskins.
- Molly Geary