The genus Arnica represents more than 25 species of flowering plants that make up the Asteraceae family. The variety used for medicinal purposes is A. montana, a species native to the mountainous regions of Europe and the Iberian Peninsula. Some effects associated with arnica include the relief of pain and inflammation, which is why it is traditionally used to address earaches. Due to toxicity, however, use of this herb is restricted to topical and homeopathic preparations.
Botanical Description
Arnica, also known as mountain tobacco and leopard's bane, is a perennial that produces yellow flower heads from May through August. Although this herb is native to the northern and southwestern regions of Europe, it is now cultivated throughout North America. However, since the plant is toxic, it is not commonly found in residential herb gardens.
Traditional Use
Historically, arnica has been used to speed wound healing and reduce pain and swelling. Native Americans frequently used arnica as a topical remedy for sprains, bruises, muscle aches, insect bites and stings, and to reduce pain and inflammation associated with arthritis, rheumatism and broken bones.
Today, arnica is widely used in homeopathy to treat sprains and bruises. Arnica preparations are available as topical creams or salves, as homeopathic tablets and as alcohol-based tinctures for use with compresses.
Chemical Composition
According to the "Physicians' Desk Reference for Herbal Medicines," arnica contains sesquiterpene lactones, a group of compounds that occur naturally in many plants that are responsible for producing allergic reactions. One of these compounds, helenalin, is poisonous in large quantities. The root of the plant contains thymol and thymol esters, the same antibacterial substances found in the herb thyme.
Anti-inflammatory Effects
The PDR states that, applied topically, the sesquiterpene lactones in arnica montana produce analgesic, antibacterial and anti-inflammatory effects. These attributes are likely why arnica is a traditional herbal remedy for earaches, but there is no clinical evidence to directly support the use of arnica for this purpose.
There is, however, evidence to demonstrate the anti-inflammatory benefits of arnica. For instance, Berthold Büchele and fellow biomedical scientists at Ulm University in Germany reported in the June 1, 2010 issue of "Analytical Biochemistry" that helenalin selectively inhibits transcription factor nuclear factor-kappaB, a type of protein complex involved in regulating immune response. In short, this means that sesquiterpene lactones, including helenalin, prevent and reduce tissue swelling.
Pain Reduction
Clinical evidence that arnica reduces pain is mixed. For example, in the April 27, 2007 issue of "Rheumatology International," Reto Widrig and colleagues reported that arnica gel reduced pain as effectively as a 5 percent ibuprofen gel in 204 patients with osteoarthritis of the hands. However, in a study led by Catherine Cornu published in the February 2010 issue of the "British Journal of Clinical Pharmacology," a homeopathic arnica preparation did not decrease pain or inflammation in patients recovering from aortic valve surgery.
Safety Precautions
The University of Maryland Medical Center says that the topical and homeopathic use of arnica is safe, but cautions that long-term use on the skin may cause irritation. Avoid using this herb if you have a known allergy to plants in the daisy family. If you are pregnant or nursing, consult a health care practitioner before using arnica.
References
- "PDR for Herbal Medicines"; Thomas Fleming, et al.; 2000
- PubMed.gov: Surface Plasmon Resonance Analysis of Nuclear Factor-kappaB Protein Interactions with the Sesquiterpene Lactone Helenalin; Büchele B et al.; June 1, 2010
- PubMed.gov: Choosing Between NSAID and Arnica for Topical Treatment of Hand Osteoarthritis in a Randomised, Double-blind Study; Widrig R et al.; April 27, 2007
- PubMed.gov: No Effect of a Homoeopathic Combination of Arnica montana and Bryonia alba on Bleeding, Inflammation, and Ischaemia After Aortic Valve Surgery; Cornu C et al.; February 2010
- University of Maryland Medical Center: Arnica
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