The products work,you just have to use them all the time and they don't get to the cause of the problem (the inside)
Birth control effects hormones by regulating them.Hormones fluctuate up and down normally,and birth control keeps them pretty steady.
Many women will get acne before their perioRAB because of hormones spiking right before.If you are on birth control,this happens less drastically so you may not break out or if you do it won't be as severe.
Some women are sensitive to the hormone testosterone, (male hormone we all have small traces of) and that causes acne too.Birth control pills cut testosterone down so it cannot have negative effects like acne,and facial hair growth.