He is questionable for Sunday's game against the Jacksonville Jaguars.
Watt is the fourth player for the Texans (1-4) to become sick this week. Receiver Jaelen Strong, cornerback A.J. Bouye and practice squad quarterback Zac Dysert all missed practices. Strong also is questionable, while Bouye is listed as probable. Watt did not miss any practices this week.
The Texans already will be without pass-rusher Jadeveon Clowney, who has a sprained ankle.
Houston has only six sacks this season, and four of them are from Watt.