Hi
altho I have no knowledge re arnica and RSD, I have used it for many years as a topical treatment for bumps, bruises, swelling etc and it works! It also helps both the swelling and pain I get in my left foot from arthritis. I buy the gel at my local Publix

a word of caution that it should *never* be used on open wounds or if the skin is broken

re internal use, it does need to be substantially diluted, which thankfully is the case with homeopathic remedies. I used the pillules (most health stores carry them) for the first time a couple of years ago when I had to have a series of tooth extractions and it definitely helped with the healing and pain. I did not even need to take the strong painkillers that the dentist had prescribed!