Phenytoin can make this pill work less well. It speeds up the way your body clears the hormones in the pill (norgestrel and ethinyl estradiol), so less of them stays in your blood. This can lower the pill's protection against pregnancy. If you take both, talk to your doctor or pharmacist about using a backup method as well.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.