Arnica montana has been widely used as a homeopathic remedy for the treatment of several inflammatory conditions in pain management and postoperative settings. This review gives an overview of the therapeutic use of Arnica montana in the above-mentioned fields also focusing on its mechanisms of action learned from animal models and in vitro studies. Arnica montana is more effective than placebo when used for the treatment of several conditions including post-traumatic and postoperative pain, edema, and ecchymosis. However, its dosages and preparations used have produced substantial differences in the clinical outcome. Cumulative evidence suggests that Arnica montana may represent a valid alternative to non-steroidal anti-inflammatory drugs, at least when treating some specific conditions.