Use DMSO if you prefer bad breath & BO, want a minimum of 20% less efficacy, and have an irrational fear of needles, which I read somewhere indicates rampaging surpressed homosexuality & a penchant for animal buggery---but don't quote me on that.
As everyone is going to tell you, inject for the best results. Get your money's worth. I've tried all three ways. I wanted to steer from the frequent injections, but learned that it's the best route to take.