Arnica
Arnica montana
Family: Asteraceae
by Gayle Engels, Josef Brinckmann
HerbalGram. 2015; American Botanical Council
INTRODUCTION
The genus Arnica comprises approximately 40 species,1,2 of which A. montana is probably the most well-known. Arnica is an herbaceous perennial in the daisy family (Asteraceae) with leaves that form a basal rosette from which emerges a one- to two-foot stalk with orange-yellow flowers.3 Though the flowers are the primary parts used medicinally, the dark brown, cylindrical rhizomes are also sometimes used.
Arnica montana is endemic to Europe, where it is relatively widespread, growing wild from Norway to the Balkans and from Spain to Ukraine.4 Divided into two subspecies, A. montana ssp. montana grows in Scandinavia and Central Europe, while A. montana ssp. atlantica occurs in southern France, Spain, and Portugal. The material of commerce is obtained, for the most part, from wild collection in Romania (for example, in grassland areas of the Apuseni Mountains of Transylvania), where over half of the estimated annual global trade quantity is harvested,5 followed by Spain (mainly in the northwestern region of Galicia and neighboring province of León), although Spain has recently become a less important source.6 Arnica is also wild-harvested to some extent in Croatia,7 as well as Ukraine, Bosnia and Herzegovina, Montenegro, Serbia, and the Former Yugoslav Republic of Macedonia.8 There is some commercial cultivation, albeit not enough to satisfy market demand, occurring mainly in Germany, France, Italy, Switzerland, and Chile, especially due to the registration and approval in 1998 of the cultivar “Arbo” for field production. There are presently two cultivars approved and protected through the German Bundessortenamt (Federal Office of Plant Varieties, Federal Ministry of Food and Agriculture): the aforementioned Arbo (owned by Bayerische Pflanzenzuchtgesellschaft e.G. & Co KG; Freising, Germany) and “Arvita” (owned by Kneipp GmbH; Würzburg, Germany).9
Additional common names for A. montana include European arnica, leopard’s bane, wolf’s bane,*10 and mountain tobacco.10,11
[Note: The flowers of Arnica species native to North America, which are not addressed in this article, are used in much the same way as A. montana. For more information on the use of North American species, see Michael Moore’s books Medicinal Plants of the Mountain West (Museum of New Mexico Press, 2003) and Medicinal Plants of the Pacific West (2011). For Native American tribal use of North American species, see Daniel Moerman’s Native American Ethnobotany database at http://herb.umd.umich.edu/.]
HISTORY AND CULTURAL SIGNIFICANCE
Arnica tinctures (hydroalcoholic extracts) and salves have been used externally for their anti-inflammatory,10,11bactericidal,11,12 antineuralgic, antirheumatic, antiseptic, counterirritant,13 and wound-healing10 effects. Arnica preparations are also used topically to treat boils, bruises,10,13 contusions, edema, hematoma, insect bites,10,11,13 joint pain (including rheumatic conditions),13 sprains,10,13 phlebitis, thrombosis,10 muscle pain,11 alopecia neurotica (sudden hair loss after a disease or injury in which the nervous system was involved), and unbroken chilblains (painful inflammation of small blood vessels in the skin occurring in response to sudden warming from cold). Historically, a root plaster was used externally for tumors,12 a foot bath containing the tincture relieved tender feet,3 and rubbing the tincture into the scalp was believed to increase hair growth.3,12 While arnica was also used in the past for canker sores and gingivitis,13 it is now generally recommended that arnica not be used orally due to its potentially toxic helenalin content.14
In 1987, the German Commission E approved the external use of arnica flowers and preparations thereof for injuries and consequences of accidents, such as hematoma, dislocations, contusions, edema due to fracture, and rheumatic muscle and joint problems, as well as for inflammation of the oral and throat region, boils, inflammation caused by insect bites, and superficial phlebitis.15
Many sources emphasize the importance of using arnica preparations on unbroken skin.14 Also, it should be noted that arnica contains chemical constituents, notably helenalin and its derivatives, that are allergenic and may cause topical dermatitis in some individuals.16
Historically, arnica had a number of internal uses that are rarely, if ever, implemented in modern phytomedicine due to the herb’s toxic effects, including cytotoxicity (destructive to cells). For example, arnica was previously used internally as a cardiotonic, CNS stimulant,10 expectorant, nervine, sedative, and to treat liver, stomach, and intestinal cancers, among other conditions.12 Arnica homeopathic products are still used internally due to their high dilution, and thus extremely low concentration, of the herb’s chemical components. The Homœopathic Pharmacopœia of the United States (HPUS) provides two arnica monographs for over-the-counter (OTC) and prescription uses: “Arnica Montana Radix HPUS” — which describes the 1X “mother tincture” (1:10) of the root for external use and the 3X attenuation level for OTC internal use† — and “Arnica Montana HPUS,” which describes the same potency preparations but for the entire plant, including the root.17
In addition to its use in traditional European medical herbalism, arnica is widely used in two other European systems of medicine: anthroposophic medicine and homeopathic medicine. For its use as a traditional herbal medicine, the European Directorate for the Quality of Medicines (EDQM) provides quality standards monographs for arnica flower and arnica tincture in the European Pharmacopoeia,18 while the European Medicines Agency (EMA) provides labeling standards monographs for prepared forms (tinctures and liquid extracts).19 For use in anthroposophy, the whole fresh flowering plant, the fresh or dried inflorescence, the fresh or dried subterranean parts, and essential oil of the subterranean parts are described in the Anthroposophic Pharmaceutical Codex.20 For arnica-based homeopathic preparations marketed in the European Union, quality standards monographs are provided in both the French Pharmacopoeia21 and German Homoeopathic Pharmacopoeia.22
CURRENT AUTHORIZED USES IN COSMETICS, FOODS, AND MEDICINES
Arnica is used commercially in cosmetics, shampoos,13,23 hair tonics, anti-dandruff products,23 and bath products,13 and arnica oil is used in perfumery.12,23 The botanical has limited food use in very small quantities (0.02-0.08%) in baked goods, candy, gelatins, puddings, frozen dairy desserts, and beverages.23
In the European Union (EU), several defined arnica preparations — in particular, alcoholic tinctures of various strengths [1:5, ethanol 60% (v/v); and 1:10, ethanol 60% or 70% (v/v)] and liquid extract of fresh flowers [1:20, ethanol 50% (m/m)] —are regulated as traditional herbal medicinal products (THMPs) requiring registration and pre-marketing authorization. Registered preparations can be labeled and marketed for cutaneous (skin) use only and are indicated for the relief of bruises, sprains, and localized muscular pain.19 For quality control, applicants must show that the herbal starting material complies with the “Arnicae flos PhEur” quality standards monograph of the European Pharmacopoeia, and that the resulting tincture conforms to the “Arnicae tinctura PhEur” monograph.18
EU Member States also have provisions for the authorization and marketing of herbal anthroposophic medicinal products as well as homeopathic medicinal products. In Germany alone, there are 843 registered medicinal products listing arnica as an active ingredient, of which 360 products are homeopathic medicines (e.g., “Arnica Oligoplex®”; Rottapharm SpA/Madaus; Monza, Italy) and 77 are anthroposophic medicines (e.g., “Arnica Planta Tota Rh D3 Augentropfen” [eye drops]; Weleda AG; Arlesheim, Switzerland). Many of the product registrations, however, are held by individual pharmacies for dispensing.24
For use in cosmetic products, the European Commission Health and Consumers Directorate lists three arnica preparations: “Arnica Montana Flower Oil” (essential oil obtained from distillation of the flowers) for perfumery, “Arnica Montana Flower Water” (aqueous solution of the steam distillate obtained from the flowers) as a skin conditioning ingredient, and “Arnica Montana Flower Extract” (extract of the dried flower heads) for masking, perfuming, and skin-conditioning functions.25
In the United States, preparations of arnica flower of several species (A. montana, A. fulgens, A. sororia, and A. cordifolia) are permitted for use as natural flavoring substances, although in alcoholic beverages only.26 Most arnica products in the US market are regulated as nonprescription, OTC homeopathic drugs (e.g., Arniflora® Arnica Gel; Boericke & Tafel; Lehi, Utah), although some are prescription drug products (e.g., TranzGel®; Gensco Laboratories; Inverness, Florida). As such, the drug must be prepared according to the specifications of the General Pharmacy and relevant sections of the HPUS. The US Food and Drug Administration-issued National Drug Code (NDC) number must appear on the label of arnica prescription drugs, but it is not required to appear on labels of arnica OTC drug products.27
In Canada, arnica is regulated as an active ingredient of licensed natural health products (NHPs) requiring pre-marketing authorization from the Natural and Non-prescription Health Products Directorate (NNHPD). The authorized use for labeling of topical application arnica NHPs (infusion, tincture, or medicated oil) is “[traditionally] used in Herbal Medicine to help relieve pain and/or inflammation in muscles and joints (e.g., sprains, bruises, joint pain).” The quality of the starting material and resulting tincture must conform to their corresponding European Pharmacopoeia monographs.28 With the same indications for use, a separate compendial monograph is provided for “Arnica – Semisolid Dosage Forms.” The only acceptable dosage forms for compendial applications citing this monograph are semisolids such as creams, gels, ointments, and salves.29 For use as a non-medicinal component of licensed NHPs, non-therapeutic dosages of arnica flower extracts are permitted for topical use as a fragrance ingredient or skin-conditioning agent.30 At the time of this writing (July 2015), there were 482 arnica-containing licensed NHPs, of which 411 product licenses list arnica, in some form, as a medicinally active ingredient.31
MODERN RESEARCH
The chemical and pharmacological properties of A. montana are well-documented. Arnica chemical constituents include alkaloids, amines, carbohydrates, coumarins, flavonoids (e.g., eupafolin, patuletin, spinacetin), terpenoids (e.g., arnifolin, arnicolides, helenalin), volatile oils (e.g., thymol, ethers of thymol), phenolic acids, resins, bitters (arnicin), tannins, and carotenoids.13,14,23 In vitro and animal studies have shown that some arnica extracts (but mostly homeopathic preparations) have anti-inflammatory32-38 and antimicrobial39 properties.
Human clinical studies have investigated topical and internal uses of A. montana herbal extracts and homeopathic products for their efficacy in treating various inflammatory conditions. Arnica extracts have been studied primarily for their topical use while studies on internal uses are limited to homeopathic products.
In 2010, a rater-blinded (i.e., a study in which rating scales are administered with no awareness of the participant’s treatment assignment to limit scoring bias), randomized, controlled trial tested a 20% arnica ointment against three other ointments for reducing laser-induced bruising, a common side effect of dermatological procedures.40 The arnica ointment, as well as a 5% vitamin K ointment, 1% vitamin K/0.3% retinol ointment, and a white petrolatum placebo, were prepared by a licensed compounding pharmacy. Healthy volunteers (n=16) who did not have a history of bleeding disorders and were not taking oral anticoagulants were provided a jar of each ointment labeled A, B, C, and D, applicators, and spot bandages to reduce cross-contamination or smearing of the ointments. Subjects then received four induced, standardized bruises that were randomized for treatment with one of the ointments. Bruises were photographed promptly after creation and at week two, and rated by a dermatologist who had no other involvement in the study. The 20% arnica ointment was significantly superior in its ability to reduce bruising compared to the 1% vitamin K/retinol and placebo oitments, but not the 5% vitamin K oitment.
A 2007 randomized, double-blind study investigated A. Vogel Arnica Gel® (containing 50 g Arnica montana fresh herbal tincture/100 g gel; 1:20 tincture ratio; supplied by Bioforce AG; Roggwil, Switzerland) versus Optifen® Gel (5% ibuprofen gel; Spirig Pharma Ltd.; Egerkingen, Switzerland) for treatment of osteoarthritis (OA) of the fingers.41 A total of 204 patients with diagnosed osteoarthritis were randomized to receive treatment with the arnica gel (n=105) or ibuprofen gel (n=99) in 4 cm strip doses three times per day for three weeks. Improvement in all parameters was similar and clinically relevant, and neither patients nor doctors could distinguish between the two treatments. The authors stated that “arnica gel is not inferior to ibuprofen gel, regarding hand functional capacity, pain intensity, number of painful joints, duration and severity of morning stiffness, or paracetamol consumption.”
An open-label, multi-center clinical study in 2005 investigated the safety and efficacy of an arnica gel (Rheuma-Gel AtroMed®; 500 mg tincture of organically grown fresh arnica flowers; 1:20, ethanol 58%; Bioforce AG; Roggwil, Switzerland). Patients (124 women, 80 men) diagnosed with rheumatic disorders of the musculoskeletal system applied a thin layer of gel to affected areas twice daily. Average baseline pain intensity was reduced significantly by nearly 50%. Efficacy was the same in patients with mild, moderate, and severe pain. Pain reduction was statistically significant in all three groups.42
An open, multicenter study, published in 2002, investigated the safety and efficacy of arnica gel (supplied by Bioforce AG; the same formula as in the study above) on OA of the knee.42 Over a period of six week, 79 patients diagnosed with mild-to-moderate arthrosis/periarthropathy of at least one knee applied a thin layer of the gel to affected knee(s) morning and evening. Six of the 79 patients experienced localized reactions to the gel, a local symptom rate (7.6%) less than that experienced with topical nonsteroidal anti-inflammatory drugs (NSAIDs; approximately 10%).43 Significant decreases in WOMAC Index (the Western Ontario and McMaster Universities Osteoarthritis Index, an accepted test for evaluation of OA of the knee) scores occurred at weeks three and six.42 Additionally, pain, stiffness, and function were improved at visits two and three. Overall, the authors concluded that arnica gel treatment was comparable to treatment with diclofenac, an NSAID used to treat arthritis.
While there are a number of clinical studies on the topical use of homeopathic arnica preparations, they are, for the most part, not as positive in their outcomes as are studies on arnica extracts. One exception is a randomized, double-blind, placebo-controlled (RDBPC) study in which topical homeopathic arnica was applied after a downhill running protocol.44 The participants in the homeopathic arnica group (n=20) reported reduced muscle tenderness, but the preparation did not affect performance markers of inflammation or muscle damage. More common are RDBPC studies that investigate homeopathic arnica cream for pain relief after eccentric exercise (pushing the muscles past their normal point of failure).45 One such study found that, rather than experiencing decreased leg pain, subjects (n=20) reported increased leg pain 24 hours after extensive calf raises. In another RDBPC study (n=19) on a homeopathic arnica gel, there was no significant reduction in post-laser bruising.46
Internal homeopathic arnica preparations have not fared much better in clinical studies. A 2003 RDBPC study (n=64) with three parallel arms assessed the efficacy of arnica for the reduction of pain after elective carpal tunnel syndrome (CTS) surgery, wrist swelling, and use of pain medication.47 No significant differences in the three arms were found in the arnica and placebo groups at day four. A 2002 randomized, double-blind comparison study (n=37) investigating the usefulness of arnica following CTS surgery had somewhat better results.48 Compared to the placebo group, patients in the arnica group experienced no difference in grip strength or wrist circumference (swelling) one and two weeks after surgery, but the arnica group had significantly less pain after two weeks.
In a randomized, double-blind, parallel-group study, homeopathic arnica performed as well as diclofenac in relieving postoperative wound irritation and patient mobility following bunion surgery.49 It was, however, inferior to diclofenac in relieving pain, and there were no significant differences in the two groups regarding postoperative use of analgesics.
Homeopathic arnica was investigated for post-tonsillectomy pain relief in a RDBPC study (n=190) and found to cause a small but significant drop in pain scores compared to placebo.50 There was no difference in secondary outcomes (antibiotic use, analgesia use, visits to doctor or hospital, day on which swallowing returned to normal, and day on which patients returned to work) between groups.
FUTURE OUTLOOK
Romania is the main producer of wild-collected arnica flowers, exporting mainly to Germany, Italy, France and Switzerland.51 Germany accounts for approximately 80% of Romania’s arnica exports.
Estimates of market demand vary considerably. Nearly 20 years ago, Dagmar Lange, PhD — a professor in the Institute of Environmental Sciences at the University of Koblenz-Landau in Germany — estimated that 50 metric tons (MT) of dried arnica flowers (equivalent to 250,000-300,000 kg of fresh flowers) and hundreds of kilograms of dried roots were used annually in Europe.52 More recently, Rolf Franke, PhD, and colleagues have suggested8 that the demand in Germany alone is about 10 MT for the pharmaceutical sector and more than 10 MT for the cosmetics sector. In 2003, Kathe et al. reported that A. montana ranked as Romania’s seventh top medicinal and aromatic plant export, with an estimated 28 MT per year for wild-collected herbs. In 2001, 20 MT were reportedly wild harvested in the Cluj region of Transylvania alone. However, Rosa Romero Franco, PhD — a professor at the University of Santiago de Compostela in Galicia, Spain — asserts that the annual demand for dried arnica flower is as high as 300 MT, although the source of her estimation is not cited.53
Natural populations of A. montana have been threatened by non-sustainable wild collection of the roots and flowers in southern and eastern Europe.4 In northern Europe, the main threat comes from changes in land use (meadow to farm). Declining numbers of grazing animals and increased fertilization (to increase meadow fodder production) are factors contributing to a reduction in arnica habitat.
The conservation status of A. montana in Europe is subject to various EU policies, habitat directives, and wildlife trade regulations.54 For example, A. montana is listed in Annex V of the European Commission’s Council Directive on the conservation of natural habitats and of wild fauna and flora, meaning that it is a “plant species of community interest whose taking in the wild and exploitation may be subject to management measures.”55 A. montana is also listed on Annex D, the Council Regulation on the protection of species of wild fauna and flora by regulating trade therein.56
Furthermore, some European countries have their own protection measures. For example, A. montana is classified as “critically endangered” on the national red list of Luxembourg; as “vulnerable” on the red lists of Bosnia and Herzegovina, Croatia, and Germany; as “extinct” on the national red list of Hungary; and as “protected” under national laws in the Czech Republic, Lithuania, and Slovenia.57 The International Union for Conservation of Nature (IUCN) recommends actions including better resource management where mowing of meadows occurs, providing land owners with financial support to graze, and controlling land use changes, i.e., converting meadows for agricultural use.
In Bavaria, where drastic declines in wild populations have been observed, the Government of Middle Franconia has implemented a botanical species protection program to manage and protect the last remaining populations from extinction, and to increase the population size in the region by targeted propagation and seeding.58 In April 2015, the German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMU) issued a joint press release with the German Federal Agency for Nature Protection (BfN) announcing a new project to protect A. montana in the State of Bavaria.59 The organizations allotted approximately €140,000 ($154,000) to support the project, which aims not only to protect arnica habitats in Bavaria’s mountain meadows, but also to demonstrate the benefits of investing in the protection of biological diversity and “ecosystem services” (i.e., benefits people obtain from ecosystems). BMU and BfN also hope to develop of a program for sustainable regional use and marketing of regional arnica products with geographical indication, and to raise public awareness about the importance of biodiversity.
In Romania, where the bulk of the arnica supply is wild-collected, considerable investment has been made towards sustainable collection and management of arnica habitats. A three-year project (2004-2007) — funded by the UK Darwin Initiative, WWF-UK in partnership with the WWF Danube Carpathian Programme, the Agricultural and Veterinary University of Cluj, and the commune of Gârda de Sus — developed a model to strengthen capacity and economic incentives for arnica habitat conservation through sustainable wild collection and trade.6,60 The company Weleda Germany was a project partner, providing information on processing and quality requirements and signing a five-year agreement to purchase the project’s wild-collected arnica, which eventually obtained organic certification.
Weleda NZ Ltd. has also financially supported a project to cultivate the German cultivar Arbo in New Zealand under certified-organic conditions.61 The project resulted in the publication of a grower’s guide for commercial production of A. montana, prepared for the New Zealand Arnica Growers’ Group.
There are also biotech projects aiming to develop cell culture techniques for indirect regeneration and biotechnological production of active ingredients of A. montana. Researchers involved in the ArnicActive Cell project, financed by the Rector’s Conference of Swiss Universities, have hypothesized that standardized production of arnica’s active constituents is possible, regardless of soil composition, climate and weather conditions, and agricultural practices.62 They believe that this work will contribute to the sustainable protection and use of A. montana in the cosmetic, endurance sports products, and pharmaceutical products industries.
With significant efforts being made in Romania in recent years to implement sustainable wild-collection standards —coupled with the development of cultivars for field cultivation and, more recently, the development of innovative biotech methods for production of active principles — the commercial supply of A. montana raw materials should become more predictable for companies willing to pay fair prices that cover the costs of sustainable production.
Regarding substitution in the marketplace, professor emeritus Günter Willuhn, PhD, author of a chapter on A. montana in Herbal Drugs and Phytopharmaceuticals (CRC Press, 2004), has reported relatively frequent adulteration with Mexican arnica (Heterotheca inuloides, Asteraceae) in the past.10 In addition, researchers from the Autonomous University of Tlaxcala in Tlaxcala, Mexico have reported that Mexican arnica was being exported in relatively large quantities, mainly to companies in the European Union and United States, for use as a substitute for A. montana.63
A European market survey carried out by the Centre de Desenvolupament Rural Integrat de Catalunya (Solsona, Spain) determined that most of the Arnica products in the Spanish market likely contained Mexican arnica. It was estimated that, in 2009, about 96% of the arnica consumed in Spain was Mexican arnica and less than 4% was A. montana. Reasons given by the respondent companies included an inability to obtain sufficient quantities of A. montana, its high cost compared to Mexican arnica, and that product companies did not include botanical names in their product specifications (only “arnica”) in order to give them flexibility to use either European or Mexican arnica in formulations. Bulk wholesaler respondents expressed interest in returning A. montana to the market but stated that it would be difficult to get companies to switch back due to the significant price difference.64
In the meantime, the Mexican Pharmacopoeia, which includes quality standards monographs for both “Arnica, Flor” (A. montana) and “Arnica Mexicana, Flor” (H. inuloides), provides botanical identification assays that enable the detection of adulteration of A. montana with flowers of A. chamissonis ssp. chamissonis, H. inuloides, and/or Calendula officinalis (Asteraceae).65
In a recent US survey of nine botanicals that had previously been reported to be adulterated or were suspected to be at risk of adulteration, 10 samples labeled “Arnica montana” were purchased from separate vendors.66 Of the 10 samples, six were H. inuloides. The authors opined that the substitution might be economically motivated as H. inuloides is larger and more abundant and accessible in its native habitat, Mexico. However, they admitted that honest confusion might also be responsible as H. inuloides is called “arnica” in Mexico, and is used similarly, e.g., for bruises.
—Gayle Engels and Josef Brinckmann
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