Arnica is a perennial plant species native to parts of Europe and Siberia. Its medicinal properties have been of special interest to herbalists for centuries. Historically, arnica was used as a popular folk remedy in various teas and tinctures for a host of external and internal ailments. Conditions of the heart, lungs, and skin were all treated with this popular herb. Although there remains little practicality for its internal usage, its homeopathic and topical applications have become extremely popular.
Germany provides a great example for arnica’s growing popularity as a nutritional supplement. Germany, alone, is credited with manufacturing over one hundred different preparations containing arnica. Arnica is so well known for its medicinal properties in fact; arnica is often called the wound herb (wundkraut), fracture herb (bruchkraut), and fall herb (fallkraut) in this region of Europe. Germany’s Committee E, an expert committee whose sole purpose is to establish credibility for various medicinal plants and herbal drug preparations, cites arnica as an effective treatment for various post-traumatic conditions.
The compounds found within the arnica plant, particularly sesquiterpene lactones, are thought to be responsible for the herb’s medicinal and homeopathic properties. Although some of these lactones are extremely toxic, sesquiterpene lactones have proved useful in reducing many inflammatory processes caused by reactions to specific allergens or soft tissue trauma. In addition to the sesquiterpene lactones, various carbohydrates, flavonoids, and essential oils found within the chemical makeup of the herb also help to define its nutritional effectiveness. Arnica may be of great interest to individuals suffering from insect bites, gingivitis, sprains, and other symptomatic inflammatory diseases.
Arnica is commercially available in numerous topical products. Its most common form of delivery is as a tincture, prepared with 70 percent ethanol. Arnica tincture is the preferred form of the herb for establishing the base of different creams and ointments. Arnica may also be taken internally via teas or extremely diluted homeopathic preparations. External delivery methods of arnica include compresses, poultices, and mouthwashes. Due to the possible toxicities resulting from its oral ingestion, it is advisable that homeopathic remedies and teas be taken under the supervision of a medical practitioner.
Pain and Inflammation
Sesquiterpene lactones, arnica’s active ingredients, and its primary component helanin, have been shown to produce certain pain-relieving and anti-inflammatory actions in post-operative patients.  A double-blind study was conducted upon 37 patients suffering from carpel tunnel syndrome. Patients who consumed either homeopathic tablets, or applied arnica ointments directly to the healing wounds exhibited a greater reduction in post operative pain than individuals receiving placebo. 
Although the direct mechanism to arnica’s analgesic an anti-inflammatory properties is largely unknown, scientists have theorized that the sesquiterpenoid lactone helenalin, and the sesquiterpenoid lactones 1 1alpha, 13-dihydrohelenalin, and chamissonolid may provide some explanation. These compounds have been reported to inhibit the activation of NF-kappaB, which is a central mediator in the immune system.  This unique mechanism of action stops the inflammation of blood vessels by inhibiting the communication of specific genes encoded for inflammatory response. This finding is promising, as arnica may one day be converted to an potent anti-inflammatory drug. This medicinal herb could, theoretically, treat severe inflammation disorders such as rheumatoid arthritis and inflammatory bowel disease in the future.
Muscle soreness caused by exercise
Due to the anti-edemic and counterirritant effects of arnica, many medical practitioners have used this herb during the early stages of muscle injury caused by demanding physical activity or direct trauma, both are characteristics which often accompany various sports. Ligament sprains and muscle strains are among the most popular injuries treated with topical applications of arnica.  Arnica tincture delivered by means of a cold compress may also provide and effective tool in alleviating bruising. Clinical trial has suggested that arnica gel applied to certain joints 2-3 times per day, may also provide for a reduction in the pain and stiffness associated with osteoarthritis.  More research is, however, needed to accurately assess arnica’s validity as an effective sports supplement.
Certain constituents of the sesquiterpenoids found in the Mexican species of arnica (Hetero inuloides) have exhibited strong antibacterial properties. Gram-positive bacteria, including the methicillin resistant strain of Staphylococcus aureus (MRSA), have been shown do be adversely affected by the inclusion of arnica into the blood stream.  Because of this quality, arnica has been used in various antiseptics, acne treatments, and topical creams for insect bites.
Current research concerning the dietary supplementation of arnica: postoperative ileus, postoperative hematomas, and childhood diarrhea. [7-9]
There are no standardized or established dosages for arnica supplementation. Different dosages are commonly used and are based upon the individual manufacturer, and their accompanying recommendations. Due to the possible toxicities linked to the oral consumption of arnica, it is suggested that the drinking of teas and supplementing of homeopathic pill solutions be approved and monitored by a physician. Common and most effective preparations of arnica:
- 1:10 tincture prepared with 70 percent ethanol
- 20-25 percent tincture, or a maximum of 15 percent arnica oil cream/ointment
- compresses/poultices diluted 3 to 10 times with water
- mouthwash; tincture diluted 10 times with water (not swallowed)
As with all nutritional supplements, it is important to check the dosage recommendations chart for each supplement manufacturer.
Although the oral supplementation of arnica containing products has proven safe in clinical settings, the sisquiterpenoid lactones found in arnica are extremely poisonous and cardiotoxic to humans. Oral ingestion of arnica by supplements/teas is not recommended without first consulting with a health care provider. Signs and symptoms associated with an acute toxicity of arnica include; dizziness, nausea, vomiting, tremors, abdominal pain, and diarrhea. The prolonged and excessive intake of arnica could possibly lead to liver and kidney damage, coma, and even death.  Arnica may also increase the risk of bleeding when taken in these extreme dosages.
As an added precaution, tinctures, compresses, creams and ointments containing arnica are not advised to be applied to tender or broken skin. Although rare, topical arnica has the potential to cause contact dermatitis in persons suffering from allergies caused by flowers containing sisquiterpenoid lactones. The internal and external supplementation of arnica remains contraindicated for those individuals suffering from either herb allergies, or a hypersensitivity to botanical members of the “daisy” family. 
There are no deficiencies of arnica, as it is categorized as a nonessential supplement.
1. Macedo SB, Ferreira LR, Perazzo FF, et al. Anti-inflammatory activity of Arnica Montana 6cH: preclinical study in animals. Homeopathy, 2004; Apr, 93(2):84-87.
2. Jeffrey, S.L., Belcher, H.J. “Use of Arnica to relieve pain after carpal-tunnel release surgery.” Altern Ther Health Med. 2002 Mar-Apr; 8(2):66-8.
3. Lyss, G., Schmidt T.J., Merfort, I., Pahl, H.L. “Helenalin, an anti-inflammatory sesquiterpene lactone from Arnica, selectively inhibits transcription factor NF-kappaB.” Biol Chem. 1997 Sep; 378(9): 951-61.
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9. Jacobs J, Jimenez LM, Gloyd SS, et al. Treatment of acute diarrhea with homeopathic medicine: a randomized clinical trial in Nicaragua. Pediatrics 1994; 93(5):719-725.
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11. Hausen BM. [Arnica allergy.] [Article translated from German.] Hautartz. 1980; 31:10-17.