I've been using MSM since reading about it on this forum a couple of months ago (thanks Mel!). I was stunned by the results, my skin calmed down really quickly. It hasn't cleared up my cystic Acne completly, but it has kept it under control. I don't get any deep painful lumps like I used to. I take 1000mg a day, sometimes 2000 if my skin needs an extra bit of clearing up.
I'm also using rosehip oil and occasionally use magnesium sulphate paste to draw out new spots - works a treat.