But Baldwin, 51, was only at Lenox Hill Hospital for an hour before being released. He later went to the set of his NBC hit show at Silvercup Studios in Queens, N.Y.
A source close to Baldwin told PEOPLE that drugs or alcohol were not behind the reason for his brief trip to the hospital.
His rep, Matthew Hiltzik, downplayed the incident and predicted it wouldn't prompt Baldwin to call out sick. "This was a misunderstanding on one person's part," Hiltzik said in a statement Thursday. "Alec was quickly released from the hospital, he's completely fine and will be at work today."
Baldwin is due to co-host the Oscars with Steve Martin March 7.
With reporting by SHRUTI DHALWALA