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Trial shows that homoeopathic arnica is no better than placebo

Susan Mayor, London

Homoeopathic arnica failed to show any advantage compared with placebo in reducing postoperative pain, bruising, and swelling in patients having elective hand surgery in results from a small randomised trial published this week.

The trial randomised 64 adults having elective surgery for carpal tunnel syndrome to three groups. The first group took three tablets of homoeopathic arnica 30C ("high potency," 30 centesimal solutions) for seven days before surgery and for 14 days afterwards. The second group took three tablets of arnica 6C ("low potency," 6 centesimal solutions) each day, and the third group took placebo tablets over the same time period.

Results showed no differences between the three groups in the primary outcome of pain (assessed by the short form McGill pain questionnaire) (P=0.79) and bruising (measured by colour separation analysis) (P=0.45) at four days after surgery.

There was also no difference in swelling (based on wrist circumference) or use of analgesic medication between the arnica and placebo groups in the study (Journal of the Royal Society of Medicine 2003;96:60-5)[Abstract/Free Full Text].

The research was funded by a charity, the Dr Susil Kumar and Jamila Mitra Charitable Trust (UK), while the homoeopathic and placebo tablets were supplied by the homoeopathic medicines manufacturer A Nelson.

One of the researchers, Edzard Ernst, professor of complementary medicine at the University of Exeter, said: "Despite its reputation as a useful intervention for preventing the effects of anticipated trauma or for treating unexpected trauma, homoeopathic arnica was no better than placebo in reducing postoperative complications."

He noted that the results were compatible with negative findings from other studies and suggested that they did not support the routine use of homoeopathic arnica for preventing or reducing postoperative complications such as bruising, swelling, or pain.

He hoped that the study would "help people to look for more effective treatments and save money by not buying homoeopathic arnica."

The research group acknowledged that more than a third of study participants showed poor adherence to the trial regimen but considered that this was unlikely to have explained the lack of difference between arnica and placebo, particularly as homoeopathic practitioners often recommend that a single dose of arnica before and after surgery is enough to speed recovery.

Homoeopathic remedies are becoming popular in the United Kingdom and in many other countries and are available from certain NHS clinics. They are based on the law of similars ("like cures like"), which states that a substance that causes specific symptoms in a healthy person can be used to treat the same symptoms in someone who is sick. Remedies undergo a process called potentiation, in which the starting solution is diluted and shaken. A remedy is thought to become more potent the more it is diluted, even though there is a very low chance of even a single molecule remaining in potencies beyond 12C (12 centesimal dilutions).

Homoeopathic arnica is derived from the alpine plant Arnica montana.

Professor Ernst considered that arnica had probably developed a reputation for healing due to positive selection bias. Some patients recovered quickly after surgery. Those who took arnica attributed their rapid recovery to this remedy and told others about it, he suggested. "Those who received no benefit from arnica were less likely to discuss the lack of effect with others," he concluded.

(Credit: MIMI KAMP) Arnica mollis, a relative of Arnica montana, the species used in the herb trade