FOR EXTERNAL USE ONLY Arnica (Arnica montana) is believed to be primarily used as an external rubbing oil or alcoholic liniment for injuries and bruises. To make oil of arnica, it is believed to simply macerate fresh or dried arnica leaves and flowers in warm sesame or olive oil for three days, then squeeze and strain through a cloth. Bottling for external use and may assist with aches, strains, bruises or injuries in which the skin has not been broken.