How soon can my combi pill work? i started it on first day of period.. been sexually active since my period was over. 2nd month on the pill

It depends: BC pills work 99% of the time when you take 100% of the required doses. If you miss a dose here and there, now you are down to 91% effective. Smokers over 35 should not take BCPs . BCPs can worsen migraines. Combination estrogen progesterone pills take effect 7 days after you start. Your period protects you from pregnancy for those 7 days. otherwise you need to use a condom 7 days