Does Zofran affect the birth control pill?

There are no known drug interactions between Zofran and the Birth Control pill. Note, however, that if you have been vomiting and unable to keep anything down, the vomiting could affect how well the birth control pill works, even if the Zofran doesn't. If your condition has been that severe, consider using a back up method of birth control, like condoms or avoiding vaginal sex, for seven days after you've been able to keep the pill down.