Arnica (Arnica montana) has been used for medicinal purposes since the 1500s and remains popular today. Applied topically as a cream, ointment, liniment, salve, or tincture, Europeans and Native Americans have used arnica to soothe muscle aches, reduce inflammation, and heal wounds. It is often the first remedy used for injuries such as sprains and bruises. Arnica in herbal form is primarily restricted to topical (external) use because it can cause serious side effects when taken internally. Arnica is often used in homeopathy, and should be taken internally only in the extremely diluted form common to homeopathic remedies. If you have any question about whether you have the herbal or homeopathic form of arnica, talk to your doctor before taking it.