Arnica is known throughout North America and Europe for its therapeutic effects, especially to help heal strains, sprains, and bruises. The flowers are harvested and used to make tinctures, homeopathic preparations, or in infused oils. The oil or tincture can be applied externally to unbroken skin to disperse stagnant blood after injuries to help allay pain and prevent bruising. Commercial preparations are widely available in drug stores, herb shops and health food stores in many parts of Europe and North America. Note: do not use the tincture or oil internally, except under the supervision of a qualified health care practitioner. Homeopathic preparations of arnica are consistently the most popular product in this category, and can be purchased over the counter. Because they are highly diluted, they are generally considered safe.