It amazed me to find out that by administering WD-40 spray directly onto my thumb joints, (badly arthritic, stiff and painful) and rubbing it in, after 10 minutes the pain is eradicated and I experience markedly greater flexibility and strength in its opposable function. I know it sounds ridiculous, but it is so remarkable that it certainly is no placebo effect. As far as there being side-effects, doctors prescribe creams, and oral medications for arthritis that have much more frighteneing side-effects associated with them including cancer. I'd rather risk a little petrochemical than the other stuff thanks.