On another board someone (seriously) mentioned urine treatment, apparently an old household method used to clear up zits. Yes, that means blotting your pimples with piss, which apparently isn't as nasty as it sounds if you drink lotsa water.
I tried the urine treatment but I just couldn't piss up that high - got it all over the walls, the mirror, the fuckin' floor, and barely any of it hit my face, much less my back, so I can't vouch for it. I guess if you have any acne on your thigh or feet that's an easy way to check if it works...