Arnica montana has been used medicinally for centuries, however there are no scientific studies that prove the medical effectiveness. The roots contain derivatives of thymol,which are used as fungicides and preservatives. Arnica is currently used in liniment and ointment preparations used for strains, sprains, and bruises. Commercial arnica preparations are frequently used by professional athletes.

The thymol derivatives concentrated in the plants roots have been clinically shown to be effective vasodilators of subcutaneous blood capillaries. A study of wound-healing after surgery to treat varicose veins found a trend towards a beneficial effect of reduction of pain and hematoma following surgery.Arnica contains the toxin helenalin, which can be poisonous if large amounts of the plant are eaten, and contact with the plant can also cause skin irritation