Azelaic acid
"I had super bad acne for about half a year and it was awful. My dermatologist, at first put me on creams like Aczone and Epiduo and an antibiotic called Doxycycline Monohydrate. My skin started to look better.The dermat switched my antibiotic to a different drug called minocycline. This cleared up my face, but started making some of my acne scars look even darker! I then switched back to my normal, until last December I began having a major allergic reaction to the Epiduo. It was awful! I stopped using it and continued with the pill and with the Aczone.  I started to break out again, and I'm hoping that starting Finacea, it will keep me acne free again!"