The only thing that ever really worked (and still works!) for me is Retin A Micro, prescribed by my dermatologist. The first month using it was rough, but after that, my skin looked better than it had since before I hit adolescence (and I'm almost 40 now). After three years of using it, I also have the added benefit of having very few wrinkles. But you have to use sunscreen consistently because it makes your skin more sensitive to the sun. I would only use this for persistent acne issues, though--not just for a few pimples on the chin. For a small area, you could try Clinique's deep cleansing emergency mask. It dries up pimples almost overnight!
