Arnica use is now backed by science, according to a New York Times post, The Alternative Medicine Cabinet: Arnica for Pain Relief.
It is believed that the plant contains derivatives of thymol, which seems to have anti-inflammatory effects. Either way, scientists have found good evidence that it works. One randomized study published in 2007 looked at 204 people with osteoarthritis in their hands and found that an arnica gel preparation worked just as well as daily ibuprofen, and with minimal side effects.
This entry is apparently the first of many that Times columnist Anahad O’Connor (I love America!) will do weekly to explore “the claims and the science behind alternative remedies that you may want to consider for your family medicine cabinet”
You can check out other entries for The Alternative Medicine Cabinet here.