Blough was examined for a head injury during Sunday's contest at San Francisco.
The Cardinals made the announcement near the end of the third quarter, and if Blough is unable to return, he'll end Week 18 having completed 14 of 18 passes for 180 yards, one touchdown and two interceptions, while turning two carries into minus-2 yards and losing a fumble. With Kyler Murray (knee) on IR and Colt McCoy (concussion) inactive Sunday, Trace McSorley took over for Blough under center.