"Methyl salicylate, as found notably in oil of wintergreen, has additional external uses as a local rubefacient and is very well absorbed through the skin: it is thus a useful application for an inflamed joint -reducing the inflammatory process while at the same time PAINLESSLY increasing the blood flow itself."

courtesy of www.herbs2000.com

on a side note. Methyl Salicylate is the active ingredient(12.7%) in deep heat.