While any medication that increases your metabolism would in theory lesson the effects of oral BCP there are no studies to back this up. As with most other drug interactions with OCPs it is unlikely that diet pills would decrease the effectiveness of birth control pills. Any questions regarding your specific medications and possible drug interactions should be discussed with your prescribing doctor or pharmacist.
While any medication that increases your metabolism would in theory lesson the effects of oral BCP there are no studies to back this up. As with most other drug interactions with OCPs it is unlikely that diet pills would decrease the effectiveness of birth control pills. Any questions regarding your specific medications and possible drug interactions should be discussed with your prescribing doctor or pharmacist.