Carr is in concussion protocol for the second time in New Orleans' last three games, in addition to suffering an injured right shoulder for the third time and a back injury.
He was sidelined in the fourth quarter against the Lions, with the Saints, 5-7 after their third consecutive loss, trailing 33-21. On third-and-17 from New Orleans' 48-yard line, Carr was hit by Detroit defensive lineman Bruce Irvin during an 8-yard completion to running back Alvin Kamara. Irvin was penalized for roughing the passer and Carr laid on the turf for several minutes as he received medical attention.
A cart was brought out to possibly transport him off the field, but he stood and walked off under his own power while favoring his right shoulder. Carr finished the day having completed 17 of 22 passes for 226 yards and a touchdown, with an interception and a lost fumble. He was sacked twice.
"He's going in for evaluation on a couple of different things," Saints Coach Dennis Allen said. "Obviously, with injuries, you've got to pay attention to that.
"I think any time you have a concussion, it's concerning. There's concern with some of the injuries that he has suffered. We'll go in and evaluate where he's at physically, and see where he's at physically, and we'll go from there."
Carr's first injury this season, a sprained AC joint in his right shoulder, occurred against Green Bay on Sept. 24. He later suffered a concussion and shoulder injury against Minnesota on Nov. 12. Neither of those two instances prevented him from starting the next game, though the Saints had a bye week after playing Minnesota.
Jameis Winston came in as Carr's replacement each time, notably throwing two touchdowns against Minnesota in the 27-19 loss. Sunday, Winston completed two of five passes for 41 yards.
"Our plan has always been that if something happened to Derek, Jameis is the quarterback and we'll use Taysom (Hill) in the same role that we've always utilized him," Allen said.
New Orleans trailed 21-0 less than halfway through the first quarter before outscoring the Lions 28-12 down the stretch.
"We got punched in the mouth early in this game, and I thought our guys fought back and battled back," Allen said.
"We're going to keep chopping wood, and that's the only thing you can do in this league. We're just going to focus on what we have to do to try to improve in those areas so that hopefully, we can eventually break through and win some of these one-score games. Because we're obviously close, and we've just got to keep chopping wood.
"Nothing positive comes out of being doom and gloom. Obviously, you've got to make the corrections that need to be made and then you've got to accentuate the positives and you've got to try to minimize the negatives. That's what you've got to be able to do."
Initially, the Saints' offense struggled and the unit was booed by the home crowd. Winston said that Carr displayed his resiliency throughout that scenario.
"From my position I'm always lifting Derek up, but from the city's position, I agree with (safety) Tyrann (Mathieu)," Winston said. "I believe that we got to give them something to cheer for. I know that can be difficult at times, but (Carr) was very resilient, he answered the bell.
"But to the fans, we function off of your support. I know that we got to come in and give you something to cheer for. But just know that you impact us because we're trying to lift you up. We're trying to put on the show for you.
"So your support, your cheering, the inspiration that you give us is...this is why we do this. We do this for you. We wouldn't have a job if it wasn't for you all. So I just encourage all y'all to get behind us. That's what this city's is about. This city's about resilience, this city's about building and staying together. Despite our record, despite what the situation that's going on, we got to stand together.
"Because the only people that can fix this is us, and that's y'all included. That's the fans. That's the team. And that's it."