There are several herbal supplements that might interfere with the effectiveness of birth control pills. Most prominent of them are Kava Kava and St. John's Wort. Both of them are used as antidepressants. However, there is no concrete proof that kava kava interferes with birth control pills effectiveness. But, medical fraternity is unanimous that St. John's Wort has proven level of negative impact on effectiveness of birth control pills.

 This drug reduces normal blood concentration. As a result birth control medications and pills lose their effectiveness. Along with birth control pills, St. John's Wort has also negative impacts on the functions of other antidepressants. If you are worried about the effect of kava kava, you are advised to take mild dosage of it.  Herbal supplements used for anti-seizure measures are also not compatible with the functioning of birth control pills and medications. 

Doctor consultation helps a lot in this regard. If you are taking any herbal supplement, tell the doctor regarding it before beginning with birth control pills. The doctor will analyze the effects and prescribe the effective medications accordingly.  Taking pills without doctor consultation might not deliver the desired results.