I had chronic acne for the entirety of my teen years and even into my 20's. I tried all sorts of things. Benzoyl Peroxide, Salicylic Acid, various mail-order subscription kits (you know the ones). Nothing worked.
I ended up getting rid of it after I went to a dermatologist that recommended I wash my face daily with Cetaphil face wash (available at just about any grocery or drug store). I also completely stopped using any and all hair products.
No hair gel. No hair spray. Nothing. Just washed my hair every morning with Head and Shoulders shampoo and rinsed, lathered up the cetaphil and applied all over my face. Let it sit for half a minute or so, then rinse. Blow dry and water for styling.
Acne solved.
Since then, I have shared this technique with a number of other people, and they were all able to solve their acne issues the same way.
I still get the occasional flare up every once in a blue moon, and I've noticed a direct correlation to whenever I eat a lot of ice cream or drink milk (even though I have been tested and don't have milk allergies). I'm not sure how it's possible, but if I drink a glass of whole milk, I can reliably count on getting at least 3 zits in the next week, after months of absolutely zero skin problems. So there is definitely something going on there.