I've read about using arnica to help bruises go away faster. How exactly does it work? Is it safe to use? Side effects?

Safe,MinmalSideEff. The active ingredients of arnica are sesquiterpene lactones, such as helenalin and 11,13- dihydrohel-enaline and chamissonolid. Also pinoresinol, epipinoresinol, phillygenin, matairesinol, nortrachelogenin, and nortracheloside (six dibenzylbutyrolactol derivatives).helenalin and dihydrohelenalin, may be responsible for anti-inflammatory and analgesic activity. **[P.S. Never worked for me]**