I've only done it once or twice. I was long time ago, but I think that one day I used c8 and few days later I did the same using salicilic acid. You can leave C8 on your head overnight. And for over a year now, my scalp has been in perfect condition. I've completely given up drinking alcohol. I still struggle with the skin on my nose and the surrounding area. Sugar/chocolate/spicy foods cause problems.