A topical remedy used in homeopathic dentistry for the management of trauma and bleeding. It has been known to cause contact dermatitis. It is derived from the rhizomatous arnica genus of plants. Current research evidence for the efficacy of arnica is lacking.
Ernst E., Pittler M. H. Efficacy of homeopathic arnica: A systematic review of placebo-controlled clinical trials. Arch Surg 1998;133:1187–90.