Arnica usually refers to Arnica montana, a mountain plant used for relief of bruises, stiffness, and muscle soreness in herbal medicine. Arnica is widely used as a salve for bruises and sprains, and sometimes as a tincture, for the same anti-inflammatory, pain-relieving purposes. It is available in natural/health food stores, most commonly in gel form, to be applied to the affected area approximately three times daily.