Palmer suffered cracked ribs and a bruised lung during Sunday's 17-6 loss to Carolina.
Allen said another quarterback will not be brought in for the regular-season finale at San Diego.
"No, I think we'll stick with Matt (Leinart) and Terrelle (Pryor), both those guys for this week," he said. "We'll get both those guys reps in practice with the first team this week."
Allen did not reveal who would start against the Chargers.
"Our plan right now is to work both of them this week and then we'll see how practice goes and then later in the week we'll be ready to name a starter," he admitted.
Leinart replaced Palmer against the Panthers.
Palmer finishes the season with 4,018 yards, 22 touchdowns and 14 interceptions.
