"i started using differin in february after dealing with horrible acne my last semester of college. i think it was stress related, because i&#039;ve always had pretty great skin up until then. i went to my dermatologist and he prescribed me differin and antibiotics. all i can say is there is hope!! it took me 12 whole weeks to have skin i was comfortable with, but it really does work. my skin was horrible at first when i began using it, the purge as people like to call it, and i really didn&#039;t think there was going to be a light at the end of the tunnel. but seriously week 12 hit and it was night and day. i still use it every night with some days off in between but now i am actually comfortable in my skin w/ only the occasional zit"