Arnica Gel - Boiron Arnica Gel is used for relief of muscle aches and stiffness, due to minor injuries, overexertion, falls, and blows. Arnica montana tincture is a medicine that has been used for centuries to relieve the aftereffects of falls, blows, sports injuries & overexertion. It makes black & blue marks go away faster & relieves the pain, swelling & stiffness caused by physical trauma.  It is a favorite of athletes, coaches & trainers.  Immediately after over-excercising or recovering a minor injury, apply Arnica Gel to ward off pain, stiffness & black-&-blue marks.