My girlfriend is on orthotricyclen. She takes azithromycin. will that decrease the effectiveness?Sources!!?

I need sources and hopefully how much the effectiveness is reduced. Also how long before it is safe to have sex again.My girlfriend is on orthotricyclen. She takes azithromycin. will that decrease the effectiveness?Sources!!?
any antibiotics will nullify the effectiveness on the Pill. thank you for at least asking this! you need to use a back-up method (condom), until the meds are finished. or don't have sex if she's still sick.
Most every antibiotic will drop the effectiveness of the pill quite a bit (both my OB GYN told me and we learned this in my woman's health semester of nursing school). You need to use back up birth control until she has been off the antibiotics for a whole 30 days. It sucks, but it's better then getting preg!