The frail 84-year-old pontiff came down with the illness Sunday and doctors advised that he cut back on his activities, said papal spokesman Joaquin Navarro-Valls.
"He has joined the more than a million Italians who have come down with the flu," Navarro-Valls said.
Among activities scheduled for the day was the presentation of the Vatican's yearbook, a duty that Navarro-Valls said was simply turned over to him. Also on the schedule were meetings with several bishops and foreign officials.
The last time the pope skipped an audience for illness was in September 2003 because of an intestinal ailment.
John Paul's voice was weak but he was otherwise in good form during a public appearance Sunday when he tried to release a dove out of his apartment window as a symbol of peace. He chuckled with children who watched in delight as the bird flew back into the room overlooking St. Peter's Square (search).
The pontiff was addressing thousands of young people from an Italian Catholic organization who marked January as a month to promote peace.