Medical Attributes of Arnica spp.

by Olivia Questore
Wilkes University
Wilkes-Barre, PA

July 2015

Arnica spp. are rhizomatous herbaceous perennial herbs that belong to the Asteraceae (aster family) (Sugier, et al. 2013). Their common names include Wolf’s-bane, Leopard’s Bane, European Arnica, Mountain Tobacco, Wolfsbane, and Mountain Snuff (WebMD n.d.). Arnica is native to both North America and Europe (Sugeier 2013). Some species of Arnica are endangered within their native region in Europe (Sugeier 2013). Within North America, Arnica is predominantly found in the North West projecting upward into Canada and South into the northern regions of New Mexico, Arizona, Nevada, Colorado, and California (Gruezo & Denford 1995). Thirty species within the genus are found in North America (USDA 2015). Primarily, Arnica’s endangerment status is due to habitat loss, but the high demand and collection for medicinal uses creates additional stress on the species (Falniowski, et al. 2013).  Arnica is found primarily in shrubland and alpine mountain environments (Falniowski, et al. 2013). Additionally, the herb can be found in pine forests, meadows, open forest edges, mowed pastures, and road/path sides (Falniowski, et al. 2013).   The genus contains many medicinally viable species, although Arnica montana is the most commercially available (Moore 2011).

Commonly, Arnica has been used to treat inflammation and prevent pain and bruising (Stevinson, et al. 2015). Internally, Arnica has been used as an immuno-stimulant, and in the 20th Century was used as a treatment for epilepsy and seasickness (EMEA 1999). Native Americans had been known to use Arnica in ointments and tinctures (Hocking 1945). In Europe, because the plant was thought to possess bactericidal and fungicidal properties, it was used to treat gunshot wounds and abrasions (Zeigler, et al. 1992).

The flowers of Arnica contain multiple therapeutic components, including arnicin, volatile oil, resin, and tannins (Willuhn 1972).  More recently, it was discovered that the anti-inflammatory properties of Arnica could actually be attributed to sesquiterpenoid lactones (Levin & Willuhn 1987, Merfort & Wendisch 1993).  Although initially cultivated for its flower heads, recent research has found that some medicinal components are also found in the herb’s rhizome (Pljevljakusic, et al. 2012). Aromatic hydrocarbons were found to predominantly comprise the essential oils found in the rhizome and were further identified as thymol derivatives (Pljevljakusic, et al. 2012).

Although, Arnica has been known to be used for wound healing promotion and pharmacological concentrations and is supported by several in vitro and clinical studies, investigations of herbal homeopathic remedies on would healing processes are rare (Hostanska, et al. 2012). In Hostanska et al.’s (2012) blind in vitro trial of wound scratch closure of NIH 3T3 fibroblasts, Arnica did not show an effect on cell viability and did not stimulate cell proliferation (Hostanska, et al, 2012). In contrast, an in vivo / in vitro study found that when Arnica is administered orally, it protects against hepatic mitochondrial membrane permeabilization induced by calcium and iron due to the fragmentation of proteins due to the attack of reactive oxygen species (de Camargo, et al. 2013). In a clinical study done in a post surgical setting for pain and inflammation, Arnica was found to be more effective than a placebo for post-traumatic and post-operative pain, edema, and ecchymosis (skin discoloring caused by subcutaneous bleeding) (Iannitti, et al. 2014). Dosages and preparations affected the efficacy of Arnica when treating pain, edema, and ecchymosis (Iannitti, et al. 2014). For instance, when given at higher dosages, Arnica was found to have side effects that outweighed the benefits, but when given at the correct dose, the efficacy improved and side effects decreased (Stevinson, et al. 2003).  Additionally, when taken orally, the efficacy was lower than when used in a topical patch form (Barkey & Kaszkin 2012).  In another clinical study, oral Arnica given pre-operatively was found to accelerate postoperative healing and resolution of ecchymosis after osteotomies in rhinoplasty surgery (Chaiet & Marcus. 2015).  Conversely, Arnica was found not to have any effect in the prevention of pain and bruising in a placebo-controlled trial in hand surgery (Stevinson, et al. 2003). However, Arnica in a topical patch form, 3x diluted, was developed to alleviate pain and numbness in the hand derived from cellulitis (Barkey & Kaszkin 2012). The Arnica patch was found provide a significant reduction of pain and assisted the hand to regain full functionality in a relatively short amount of time (Barkey & Kaszkin 2012).

Interestingly, Arnica has additionally been found to cause contact dermatitis and eczema when applied at excessive concentrations (Lewis & Elvin-Lewis 2003).  Despite its immunosuppressive action, Arnica has been classified as a plant with strong potency to induce allergic contact dermatitis (Lass, et al. 2008). This reaction, immuno-stimulation, is caused by the same sesquiterpenoid lactones that cause anti-inflammatory and immunosuppressive responses when dosages are too low (Lass, et. al. 2008). The lack of adequate patch testing in cases of suspected contact allergic dermatitis, incomplete or misleading product labeling, and the risk of chemical adulteration may present further concern regarding the application of botanical products, in this specific case, Arnica products (Corazza, et al. 2009).

Overall, Arnica appears to be an effective treatment for inflammation and ecchymosis. The benefits of taking Arnica orally may be outweighed by the risks, and should be used more commonly as a topical treatment. Additionally, too concentrated or too diluted forms of Arnica topically can be harmful causing allergic contact dermatitis and patient’s using this homeopathic method should be made aware of possible side effects. Further, patients should be aware that labeling on non-FDA approved bottles may not be correctly dosed and/ or prepared. Though many conflicting studies, it appears that Arnica may be useful to topically treat edema and ecchymosis, specifically following surgery or traumatic injury.


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This paper was developed as part of the BIO 368 - Medical Botany course offered at Wilkes University during the summer of 2015. Course instructor was Kenneth M. Klemow, Ph.D. ( The information contained herein is based on published sources, and is made available for academic purposes only. No warrantees, expressed or implied, are made about the medical usefulness or dangers associated with the plant species in question.

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