Date Last Updated: 01/11/04

Arnica creams, gels and sprays for the treatment of soft tissue injury

Overview

Injuries from bumps, falls and other accidents can cause bruising and swelling to skin and muscles. A number of treatments are available to help reduce swelling and bruising, including the application of creams, gels and sprays containing extracts from the herb arnica montana (arnica) to injured areas of skin and muscle. This evidence summary identified two clinical trials (involving 56 people) on the use of arnica for the treatment of soft tissue injury. One case series study was also identified in which patch tests of plant extracts were undertaken on 443 patients suffering from contact dermatitis. Overall, the results from the trials and the case series indicate that the application of creams and gels containing arnica to areas of soft tissue injury has little or no effect on bruising or swelling. There is some evidence however that arnica may help relieve pain associated with bruising and swelling. Side effects associated with the use of topical preparations of arnica appear to be mild and reversible and include localised rash, itching, red spots and dry skin at the site of application. People with contact dermatitis may also react to arnica extract. Severe and potentially lethal side effects are associated with the ingestion of the essential oil or the arnica plant itself, and only the homoeopathic preparation of arnica is safe for oral use.

Background

Soft tissue injury
Falls, sudden forceful contact with a blunt instrument, and surgery often result in bleeding and inflammation deep in the muscle fibres. Symptoms of acute inflammation include pain, heat, redness, and swelling. Some bruising may also accompany this process. Although the inflammatory process is vital to the process of muscle regeneration and healing, it can cause further swelling which can be detrimental to the healing process. The goal of treatment for such injuries is to minimize bleeding and bruising, and to control pain.

Arnica
Arnica (Arnica montana) is an alpine herb native to the mountains of Siberia and central Europe.¹ Arnica grows from a cylindrical hairy bulb with a creeping underground stem.² The flowers are scented and daisy-like, and have 10-14 bright rays each with three notches at the end. Arnica is also known as leopardsbane, wolfsbane, and Mountain tobacco.² The flower head of arnica is the main part used in herbal medicine.² Traditionally, arnica has been used as a herbal medicine throughout North America, Germany and Russia, since the 16th century.

Sesquiterpene lactones are considered the active constituents of arnica and are thought to help reduce inflammation (anti-inflammatory) and reduce pain (analgesic).² Through this action, arnica helps improve blood flow to areas of tissue damage, thereby assisting in the healing process.³ Arnica is also said to have some antibiotic activity. Arnica also contains two toxins, namely lobeline and myristic acid (found in the essential oil of arnica).^{2, 3}

Arnica creams, gels and sprays can be obtained as “over the counter” products from health food shops, supermarkets, pharmacies, etc. A medical herbalist may also prescribe arnica. The practice of herbal medicine is not currently regulated by legislation in New Zealand, however many herbal medicine practitioners are affiliated with a self-regulated professional body (such as the New Zealand Association of Medical Herbalists).

Evidence reviewed in this summary

Efficacy information

Systematic reviews: No systematic reviews on the use of topically applied arnica for the treatment of soft tissue injury were identified for this evidence summary.
Clinical trials: Two randomised controlled trials involving a total of 56 people were identified for this evidence summary.^{4, 5} No clinical trials of topically applied arnica for soft tissue injury are known to be currently underway (see www.controlled-trials.com).

Safety information

Systematic reviews: No systematic reviews on the safety of using topically applied arnica for the treatment of soft tissue injury were identified for this evidence summary.
Clinical trials: Side effects related to the use of topically applied arnica for the treatment of soft tissue injury were reported by the two trials identified in the above efficacy section.^{4, 5}
Case-control studies/Cohort studies/Case Series studies: One case series involving a total of 443 people was identified that reported on side effects related to the use of topically applied arnica, as well as skin contact with arnica plants.⁶

Evidence on efficacy

Information on the use of topical applications of arnica for the treatment of soft tissue injury is available from two clinical trials^4,5. Results from the trials indicate that topical applications of arnica have no clear effect on bruising after facial surgery⁴ or swelling in the wrist,⁵ although there is some effect on pain reduction two weeks after surgery for carpal tunnel syndrome.⁵ The results regarding pain relief should be interpreted with caution given the small size of the study. Specific results are as follows:

In one trial (involving 19 people), participants with soft issue injury resulting from laser surgery for facial telengiectases (red spots) were randomised to receive either arnica gel or a placebo gel for a two week period.⁴ No significant difference in bruising was noted between the treatment group and the placebo group at the end of the two week period.⁴
In the second trial (involving 37 people), patients received either a placebo or a combination of homoeopathic arnica tablets (D6) and arnica ointment for a four week period, prior to and following surgery for carpal tunnel syndrome.⁵ No significant difference in swelling in the wrist was noted between the treatment group and the placebo group two weeks after surgery.⁵ However, there was a significant reduction in pain after two weeks in the arnica treated group. Since the treatment group in this trial received both homoeopathic arnica tablets and arnica ointment, it is not possible to determine the individual effects of these products on the outcome.

Evidence on safety

Information on the safety of using topical arnica for the treatment of soft tissue injury is available from two small clinical trials^{4, 5} and one case-series study.⁶ Overall, side effects associated with the use of topical applications of arnica tend to be mild and reversible and include itching, localized rash, red spots, and dry skin at the site of application⁴. In one trial, the overall tolerability of the gel was rated as “good” or “fairly good” by 87% of participants at a follow-up visit.⁵ Furthermore, 76% of participants indicated that they would use the gel again.⁵ In the case series study, 443 people diagnosed with contact dermatitis were patch-tested for allergies to a variety of flowers and herbs (including arnica) to find the source of the allergen causing the dermatitis. Five people (1%) had positive allergic reactions to arnica.⁶ Three of these people had used arnica as a topical remedy, although it was not stated in what form it was applied. The remaining two people that reacted to arnica were hobby gardeners and therefore likely to have come into contact with the plant, although it was not possible to determine if arnica was the sole cause of the dermatitis in these people.

It is important to note that the arnica herb and the essential oil made from the herb should not be eaten as an overdose of arnica extract can result in vomiting, diarrhoea, and excessive bleeding (haemorrhage)². A number of publications state that deaths have occurred in people who have eaten the flowers or the arnica herb, although no documented evidence of these deaths could be located for this evidence summary.

Cited references

To find out more about any of the references listed below go to the "About page" of this website and read the section titled "How can referenced articles be obtained."

Mayor S. Trial shows that homoeopathic arnica is no better than placebo. British Medical Journal 2003;326(7384):303-303.
Hanrahan C. Arnica. In: Krapp K, Longe J, editors. The gale encyclopedia of alternative medicine. Framington Hills, Michigan: Gale Group; 2000.
Hattaway V. Arnica. New Zealand Pharmacy 2000;20(Apr):22-24.
Alonso D, Lazarus M, Baumann L. Effects of topical arnica gel on post-laser treatment bruises. Dermatologic Surgery 2002;28(8):686-688.
Jeffrey S, Belcher H. Use of Arnica to relieve pain after carpal-tunnel release surgery. Alternative Therapies in Health and Medicine 2002;8(2):66-68.
Reider N, Komericki P, Hausen B, Fritsch P, Aberer W. The steamy side of natural medicines: contact sensitization to arnica (Arnica montana L.) and marigold (Calendula officinalis L.). Contact Dermatitis 2001;45(5):269-272.

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