Newsome returned to Baltimore on Monday and got back to work at the Ravens' training complex after remaining overnight at a Chicago hospital for observation following a 23-20 overtime loss Sunday to the Chicago Bears at Soldier Field.
"It's good to see Ozzie here," Harbaugh said Monday during his weekly press conference. "He's been here all afternoon working. So, he's back and he has a clean bill of health. We don't know exactly what caused the situation, but it wasn't anything serious. So, he's doing fine."
After watching the five-hour game that was delayed by severe weather from the press box, Newsome, 57, was sweating profusely while riding on an elevator down to the Ravens' locker room. He was later transported from the stadium via an ambulance to a local hospital to undergo more tests.
Harbaugh said he first learned that Newsome wasn't feeling well after conducting his postgame press conference.
"At that point in time, they said they thought he was OK," Harbaugh said. "They had done all the tests, so they didn't think it was anything serious. But they had to keep him overnight for observation just to make sure. I know they ran tests pretty much all night, Ozzie said."
"I'm fine," Newsome told The Baltimore Sun on Monday morning on his way back to Baltimore from Chicago. "All my tests were normal and there is nothing wrong with me. They didn't find anything. I'll begin breaking down film this afternoon. It's back to work."
A fitness enthusiast who frequently works out twice per day, Newsome said it was unclear what was bothering him. He has no known health issues.
"No, just one of those things, I guess," Newsome said. "We don't know right now."
Meanwhile, Harbaugh didn't provide any injury updates on his players. That included Pro Bowl nose tackle Haloti Ngata, but the coach said there were no serious injuries emerging from Sunday.
"We'll have our injury report on Wednesday, but we look pretty good there," Harbaugh said. "We'll have more on Wednesday."
Ngata missed the game with a left knee injury after not practicing all week. He attempted to practice Friday, but was unable to go.
Ngata declined an interview request after the game, but wasn’t limping noticeably.
When asked if Ngata didn't play because of the sloppy field conditions, Harbaugh declined to elaborate on the reasons for his inactive status.
"I'm not getting into all that," Harbaugh said. "There's no reason for us to put that out there publicly. What advantage would there be for us to comment on that?
"It wouldn't help us, but I appreciate you asking. I understand why you do. It's fair, in all honesty. I just don't want to put that out there right now."
The Ravens started backup Terrence Cody at nose tackle with Ngata sidelined. He was held to one tackle.
"We hope Haloti’s back soon," Cody said. "If he’s not, I got to carry the load.”