So for the longest time I thought that taking antibiotics affects birth control. So when my doctor tried to prescribe me an antibiotic to treat my acne I was hesitant. Then I asked my doctor and he said that the studies done which claim that antibiotics lessen the effects of birth control were actually done on mice in the 70s and that the WHO actually does NOT recommend backup birth control when taking antibiotics. Long story short, women have been unduly worrying about a greater risk of pregnancy when on antibiotics for no apparent reason. So now I'm taking the antibiotic doryx for my acne along with seasonale for birth control and behold, I have fewer breakouts and fewer periods.