The former Dawson's Creek star was celebrating the end of 2012 in Mexico with her husband Marc Silverstein and four-year-old daughter, Birdie, when she became violently sick after a meal.
And Philipps admits it was a scary experience because she was worried her illness might affect her unborn baby.
She says, "I feel, like, when you're pregnant, getting food poisoning is a little scary and awful. But it was New Year's Eve, at 11.35, I started puking. And I threw up every 20 minutes for nine hours...
"It was awful. That's how I rung in my New Year. My husband came in rubbed my back and was like, 'Happy 2013 baby,' and I'm like, 'Nowhere to go but up!' But it was, like, just the worst."