3 February 2003

Homeopathic arnica "no better than placebo"

The results of a new clinical trial on a popular homeopathic remedy will appear in the February Journal of the Royal Society of Medicine.

The study was carried out by Professor Edzard Ernst and colleagues at the University of Exeter and the Royal Devon & Exeter Hospital. They looked at three groups of patients who were about to have surgery on their wrists for carpal tunnel syndrome. One group was given 'high-potency' (30C) homeopathic arnica tablets to be taken before the operation and afterwards for two weeks. Another group was given 'low-potency' (6C) tablets and the third was given a placebo. Results showed "no significant difference" in pain, bruising or swelling between the groups.

Professor Ernst sees a positive message in the findings and hopes that this research "will help people to look for more effective treatments and save money by not buying homeopathic arnica".

Using arnica for bruises
Arnica tablets are available in most High Street chemists and are usually sold to control bruising, reduce swelling and generally help recovery after an injury or operation. It is one of the most popular and well known homeopathic remedies. Although there are lots of anecdotes about cases where arnica 'really works', scientific studies have produced contradictory results. The authors suggest that "many of these trials have methodological limitations that make the findings unreliable." Their own project, a double-blind placebo-controlled randomized trial, was designed to be a more rigorous investigation.

Measuring results
Patients filled in a standard pain-assessment questionnaire before and after surgery. They recorded their symptoms and use of painkillers in a daily 'pain diary'. The hospital analysed photographs of patients' wrists, using computer software to measure exact shades of bruising. They also measured changes in swelling around the wrist. There was no significant difference between any of the groups in terms of pain, bruising, swelling, or the number of painkillers the patients had taken.

Why does arnica have such a reputation for healing?
Professor Ernst's answer is "positive selection bias". Some patients recover quickly from surgery, and if they have been taking arnica, they tell their friends that the remedy helped. If they recover well without arnica, or they took it but recovered slowly, they are much less likely to tell everyone their experiences and "the myth becomes reinforced".

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