Most complementary medicines for the treatment of rheumatoid arthritis (RA) are ineffective, according to an evidence-based report.
The report, launched by the Arthritis Research Campaign (arc), found "considerable variations" in the level of scientific data to support the effectiveness of complementary and alternative medicines on the market – of which evidence from randomised controlled trials was available for only 40.
The report says the available data shows that nearly two-thirds of compounds used for RA (the most common inflammatory arthritis) have "no or little effect", while the effectiveness of glucosamine, a supplement popular with people with osteoarthritis (OA) is again called into question.
Effectiveness is measured by improvements in pain, movement or general wellbeing.
The medicines investigated for RA include homeopathy, blackcurrant seed oil, collagen, eazmov herbal preparation, flaxseed oil, green-lipped mussels, Chinese herb tong luo kai bi and willow bark.
By contrast, fish body oil scored five out of five for people with RA, reducing joint pain and stiffness.
Safety considerations were also raised, as a quarter of the compounds were given an "amber" classification, indicating important side-effects had been reported, and a "red" safety classification was issued against thunder god vine for RA.
Professor Gary Macfarlane, who led the research, said it was important that people with arthritis had some guidance on the complementary medicines available.
"While over 60% of people with arthritis or other aches and pains use some form of complementary and alternative medicine – and find different things work for them – it is useful to also have the scientific evidence available and just as important to know how safe we think they are to use," he said.
In the UK, 46% of people use complementary medicine at some point in their lives for a wide range of conditions, spending over £450m a year on products and treatment outside conventional therapy.
The arc report, the first of its kind dedicated to arthritis, has been produced to help people make up their minds about products for which claims have been made but in many cases are unsubstantiated by hard evidence.
Professor Alan Silman, arc's medical director, said: "Complementary medicines are widely used by people with arthritis as they seek to avoid taking potentially harmful drugs, preferring natural products.
"However, 'natural' does not mean they are either safe – or effective. Many people spend hundreds of pounds on these products and they need to know that there is a strong chance of benefit."