1. Heals Bruises
A bruise is a discolored area of the skin on the body, which is caused by an injury or impact rupturing the underlying blood vessels. Healing a bruise fast by natural means is always desirable. One excellent natural remedy for bruises is arnica oil. Simply apply the arnica oil to the bruise twice daily (as long as the bruised skin area is unbroken).
A study out of Northwestern University’s Department of Dermatology found that topical application of arnica was more effective at reducing bruises than low-concentration vitamin K formulations. Researchers identified a number of ingredients in arnica that account for anti-bruising, including some that are caffeine derivatives.
2. Treats Osteoarthritis
Arnica has been shown in studies to be effective against osteoarthritis, making it an effective natural arthritis treatment. The use of topical products for symptom relief is common when it comes to osteoarthritis. A 2007 study published in Rheumatology International found that topical arnica was as effective as a nonsteroidal anti-inflammatory drug-like ibuprofen in the treatment of osteoarthritis of the hands. 
Arnica was also found to be an effective topical treatment of osteoarthritis of the knee. A study out of Switzerland evaluating the safety and efficacy of topical arnica had both men and women apply arnica twice daily for six weeks. The study found that the arnica was a safe, well-tolerated and effective treatment of mild to moderate osteoarthritis of the knee.
3. Improves Carpal Tunnel
Arnica oil is an excellent natural remedy for carpal tunnel, inflammation of a very small opening just below the base of the wrist. Arnica oil helps with the pain associated with carpal tunnel and ideally can help sufferers to avoid surgery. However, for people who decide to have surgery, studies have shown that arnica can relieve pain after carpal tunnel release surgery.
In a double-blind, randomized comparison of arnica administration versus placebo post-surgery in patients between 1998 and 2002, the participants in the group treated with arnica had a significant reduction in pain after two weeks. Arnica’s potent anti-inflammatory effects make it a smart choice for carpal tunnel syndrome.
4. Relieves Sprains, Muscle Pain & Other Inflammation
Arnica oil is a potent remedy for various inflammatory and exercise-related injuries. The positive effects of topically applying arnica have proven to be effective in reducing pain, indicators of inflammation and muscle damage, which in turn can improve athletic performance. Study participants who used arnica had less pain and muscle tenderness 72 hours after intense exercise, according to the results published in the European Journal of Sport Science.
Arnica has been used in traditional medicine for everything from hematomas, contusions, sprains and rheumatic diseases to superficial inflammations of the skin. One of the constituents of arnica that makes it such a potent anti-inflammatory is helenalin, a sesquiterpene lactone.
In addition, the thymol found in arnica has been found to be an effective vasodilator of subcutaneous blood capillaries, which helps facilitate the transport of blood and other fluid accumulations and acts as an anti-inflammatory to aid normal healing processes. Arnica oil also stimulates the flow of white blood cells, which process congested blood to help disperse trapped fluid from the muscles, joints and bruised tissue.
reference :
see PDF file Click here :