Spokeswoman Dot Joyce said the mayor could be released from Brigham and Women's Hospital Saturday or Sunday, The Boston Globe reported.
"The issue he had associated with the medication is progressing well," Joyce said. "Hopefully sometime over the weekend, he'll be released."
Menino, 67, spent three days in the hospital over the Thanksgiving holiday because of a bacterial infection he contracted during a trip to Italy.
Doctors diagnosed him with cellulitis, a skin infection, and septic bursitis in the left elbow. The 5-term mayor also has the gastrointestinal disorder Crohn's disease.
After returning home from Italy, Menino underwent minor surgery to remove bacteria from his elbow. He had returned home from the hospital, but he fell ill Tuesday.
Joyce said his doctor thinks the mayor had a negative reaction to pain medication.
"The mayor is otherwise in fine health,'' Joyce said