I had really bad acne — I was on Roaccutane for a while which really did work but after I finished the course of that drug the acne returned, but definitely not as severe!
For me reducing my intake of red meat, tomato, orange juice and chocolate really helped but when I stopped drinking tap water here in Ireland my acne cleared up!
The chemicals in the tap water in Ireland really messes with my skin so it's bottled water for me and now I hardly ever get a spot!