If I am using enzyme inducers (such as Dilantin the antibiotics rifampicin or griseofulvin, or St. John's Wort), will it make emergency contraceptive pills less effective?

<p>Medications and herbal supplements that may make regular birth control pills less effective may also reduce the effectiveness of emergency contraceptive pills. So if you are using an enzyme inducer, it probably makes sense to increase the dose of EC. You should talk to your doctor about how much to increase the dose.</p>