Arnica was recognized in the United States Pharmacopoeia in 1820. Germany alone has manufactured more than 100 drug preparations containing arnica (Kowalchik and Hylton 1997). For many years, it has been used as a cream, ointment, soothing liniment, and salve for muscle aches, inflammation, and wound healing by both Europeans and Native Americans alike. In the U.S., it has most frequently been used as a tincture for topical application (Robbers and Tyler 1999).

A randomized, double-blind, placebo-controlled trial conducted in Norway in 1995 investigated the effects of the homeopathic remedy Arnica on cell damage and muscle soreness in participants of the Oslo marathon (Tveiten et al. 1998). The long-distance runners were given Arnica in pill form or placebo twice daily, before, during, and after the race. The results indicated that arnica significantly reduced muscle soreness (measured by a visual analogue scale) but did not affect muscle cell damage (determined by serological evaluation). However, results from another randomized, double-blind, placebo-controlled clinical trial indicated that a homeopathic preparation of Arnica (30X) did not significantly reduce muscle soreness in long-distance runners (Vickers et al. 1998). Use of Arnica as a homeopathic remedy is distinct from use of arnica as a topical preparation or internally as an herb. As an herbal remedy, arnica is primarily restricted to topical external use because of concerns about severe side effects associated with systemic use (Blumenthal et al. 1998).

Arnica is a perennial with a round, hairy stem ending in one to three flower stalks (Bisset 1994; Gruenwald et al. 1998; Kowalchik and Hylton 1997). Flowers are yellow-orange ray flowers around a cluster of tubular center flowers, similar to the daisy. They aretwo to three inches across. Leaves are bright green, toothed, and slightly hairy on the upper surface, and lower leaves have rounded tips. The plant grows to a height of one to two feet and is found in the mountains of Europe and Siberia and cultivated in North America.

Fresh or dried flower heads (Bisset 1994; Blumenthal et al. 1998; Weiss and Fintelmann 2000)

Sesquiterpene lactones (including helenalin, dihydrohelenalin, arnifolin, chamissonolide, and arnicolides), flavonoid glycosides (including isoquercitrin, luteolin-7-glycoside, and astragalin), volatile oil (about 0.3%, with thymol and its derivatives), phenolic acids (including chlorogenic acid, cynarin, caffeic acid), and coumarins (umbelliferone, scopoletin) (Bisset 1994; Blumenthal et al. 1998; Gruenwald et al. 1998; Robbers and Tyler 1999; Schmidt et al. 1998).

Actions: counter-irritant, antimicrobial, anti-inflammatory, antiseptic, antiphlogistic, antirheumatic, antineuralgic, respiratory-stimulant, positive inotropic, reduce edema (Bisset 1994; Blumenthal et al. 1998; Robbers and Tyler 1999)

Traditional Uses

Topically: acne, bruises, sprains, muscle aches, wound healing, superficial phlebitis, thrombosis, arthralgia, rheumatic pain, inflammation from insect bites, hematomas, contusions, fracture-related edema (Bisset 1994; Blumenthal et al. 1998; Gruenwald et al. 1998; Lussignoli et al. 1999; Lyss et al. 1997; Schulz et al. 1998)

Internally: senile heart, angina, coronary artery disease (Weiss and Fintelmann 2000)

Gargle: sore throats, pharyngitis, smoker's cough (Weiss and Fintelmann 2000)

Clinical Applications: An injectable homeopathic preparation that contains arnica as one of 13 active ingredients has demonstrated promise in clinical use for trigger point and joint injections (Conforti et al. 1997). The standard dose is one ampule mixed in the syringe with 3 to 5 ml of local anesthetics. Anecdotal reports are positive but further clinical studies are needed.

Experiments have demonstrated that the sesquiterpene lactones, helenalin and dihydrohelenalin, along with their ester derivatives, are the medicinally active constituents of arnica that exert anti-inflammatory effects (Lyss et al. 1997). Antimicrobial and anti-edema effects have also been attributed to these substances (Bisset 1994; Robbers and Tyler 1999). Animal research supports the ability of arnica to reduce edema associated with local trauma (Conforti et al. 1997; Lussignoli et al. 1999). German researchers in 1997 showed that helenalin and its ester derivatives selectively inhibit activation of transcription factor NF-kappaB (Lyss et al. 1997). Helenalin does this by modifying the NF-kappaB/IkappaB complex, preventing the release of IkappaB. Researchers concluded that anti-inflammatory effects of helenalin are due to a molecular mechanism that differs from that of other nonsteroidal anti-inflammatory drugs (NSAIDs), including indomethacin and acetylsalicylic acid.

The most commonly used forms of arnica are based on a 1:10 tincture prepared with 70% ethanol (Gruenwald et al. 1998). Creams and ointments use 20% to 25% tincture or a maximum of 15% arnica oil made from 1 part drug and 5 parts vegetable oil (Blumenthal et al. 2000; Gruenwald et al. 1998). For use in compresses, the tincture is diluted 3 to 10 times with water.

Infusion: 2 g of herb steeped in 100 ml of boiling water, then strained (Bisset 1994; Blumenthal et al. 1998)

Mouthwash: tincture is diluted 10 times with water and should not be swallowed (Blumenthal et al. 1998; Gruenwald et al. 1998)

Poultice: tincture is diluted 3 to 10 times with water (Gruenwald et al. 1998)

Arnica is also available as a homeopathic remedy. Follow the instructions on the product labeling for dosages and duration of administration.

Arnica is rarely used internally because it can cause dizziness, tremors, tachycardia, and arrhythmias (Weiss and Fintelmann 2000). It may also irritate mucous membranes and cause vomiting. Internal use should be limited to skilled clinicians who understand its pharmacology and toxicology.

Prolonged topical treatment can cause edematous dermatitis with pustules, eczema, or toxic skin reactions with formation of vesicles or necroses; the active constituent helenalin and its esters are allergenic and may cause topical dermatitis (Bisset 1994; Blumenthal et al. 1998; Gruenwald et al. 1998; Robbers and Tyler 1999).

As an herb, arnica should not be taken internally unless prescribed by a trained clinician (Bisset 1994; Gruenwald et al. 1998; Robbers and Tyler 1999; Weiss and Fintelmann 2000). Homeopathic doses are very dilute and generally considered safe when used in accordance with the product labeling.

Use of arnica is contraindicated in people with allergy or hypersensitivity to arnica (Blumenthal et al. 1998). Avoid topical use of arnica on broken skin, as in the case of leg ulcers.

While there are no specific restrictions against usage during pregnancy or breast-feeding, in general it is better to refrain from using any medications during this time unless absolutely necessary.

No clinically significant interactions between arnica and conventional medications are known to have been reported in the literature to date, including the German Commission E monograph (Blumenthal et al. 1998).

The German Commission E has approved arnica for topical use as an anti-inflammatory, analgesic, and antiseptic (Blumenthal et al. 1998).

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Vickers AJ, Fisher P, Smith C, Wyllie SE, Rees R. Homeopathic Arnica 30X is ineffective for muscle soreness after long-distance running: a randomized, double-blind, placebo-controlled trial. Clin J Pain. 1998;14(3):227-231.

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