Actress Annie Mumolo has revealed that behind the laughs and bad behaviour in the summer hit, she and her castmates were all sick.

Promoting the upcoming DVD and Blu-ray release of the film in America, Annie admits she was "in survival mode" most of the time.

"Everybody had the flu at some point, so everybody was supporting each other through the various stages of it," she recalls.

"Actually Jada Pinkett Smith and I had it at the same time. Christina (Applegate) was so sweet. She sent me a get well hot toddy box with a bottle of Jack Daniels, honey and lemon, which I would drink at night when I wasn't working.

"It was the worst flu I've had since I was 18. It was really, really, really bad. I remember Jada calling me at one point and saying, 'I think I need to go to the hospital', and I said, 'Yeah, I might too but let's give it one more day, because I really think I might be dying in this hotel room!' It was pretty terrible.

"I had a really high fever and we were outside and it was, like, 40 degrees in New Orleans, where we were shooting, in January...," she tells WENN. "I got back to the hotel room and tried to get room service, so it was a little tricky waiting 45 minutes for your soup. It was really brutal and lasted for about three weeks."

Her illness spoiled the enjoyment of watching the movie: "When I see the movie all I think about is what I felt every day in every scene: 'Oh God, I'm gonna die!' Professional hair and make-up at least got me looking human. That flu was rough. I did get sad and wish for my mom at one point, because I was really sick."

"You can't call in sick on movies, so it was like, 'How much can you keep injecting me to keep me moving and standing'. The doctors on set gave you shots according to your symptoms. They gave us antibiotic shots and shots of B12. They were treating a lot of people on this one."