Among the ill was Dianna Agron, who plays the show's head cheerleader, Entertainment Weekly reported.
The illnesses forced cancellation of Friday's taping and cast members who remained healthy got the day off.
Agron, Tweeting from her bed, said: "Note to self. Should have gotten a flu shot. In bed, hoping that medicine, soup, my computer and a marathon of movies will be the cure."
Cast member Lea Michele was in higher spirits, tweeting: "What a beautiful relaxing day! Went on an awesome hike and just (got) a massage! So happy it's the weekend!"
Mark Salling used the time off to play golf.
"Nothing like a little golf on an unexpected day off," he tweeted.
Production of the show was expected to resume Monday.