Herb cures that 'do you more harm than good'

They say there is no evidence these therapies work or that they are safe to use.

Individualised treatments, used in Chinese, Ayurvedic and Western herbal medicine, have become increasingly popular over the past 20 years.

Practitioners mix different combinations of plant extracts to treat ailments such as asthma and arthritis.

Scroll down for more

But the researchers from Peninsula Medical School, Exeter, said these mixtures should be banned.

The team looked at 1,300 published articles on the subject and analysed the only three found to be randomised clinical trials.

These three trials investigated the treatment of osteoarthritis of the knee, irritable bowel syndrome and the relief of side effects caused by drug treatment for cancer.

In two of the studies there was no statistical difference in the results from tailored herbal medicine and a placebo, or dummy treatment.

Tailored herbal medicine therapy seemed to work better than a placebo for irritable bowel syndrome but was not as effective as giving patients standard herbal preparations.

Writing in the Postgraduate Medical Journal, researcher Dr Peter Canter said: "Our conclusion is therefore overall that there is no convincing evidence that individualised herbal medicine works in any indication."

In fact, he said, there were serious safety risks involved, such as adulteration of ingredients with poisonous or banned substances, and interaction

with other herbs or medicines.

Dr Canter said many studies did promote the effectiveness of herbal medicines, but most were examining standard preparations or single herb extracts.

Britain is reviewing the laws on the regulation of tailored herbal treatments, but Dr Canter wants them banned, even at the risk of a backlash from Chinese or Indian communities.

He said: "It seems to me if you look at a drug in mainstream medicine it doesn't get used on a patient until its efficacy has been demonstrated."

Professor Edzard Ernst, professor of complementary therapy at Exeter University, said the public could not differentiate between different types of herbal medicine.

In some countries doctors practise phytotherapy, which uses extracts from a single plant and closely follows the principles of pharmacology.

But this can be confused with traditional herbal medicine and the £191million industry in over-thecounter remedies - neither of which currently has a basis in science.

Jane Gray, of the National Institute of Medical Herbalists, said: "We would challenge the conclusions reached by this study based on such little data.

"We want more research, but we're all in private practice and cannot afford to stop earning to run a trial over several months."

She added: "These individualised treatments do work. Ayurveda, traditional Chinese medicine and western herbal medicine have strong historical traditions, and every day we see satisfied patients who get better."

There are around 1,000 registered individualised herbal medicine practitioners in the UK and an estimated 3,000 Traditional Chinese medicine practitioners, but it is not necessary to register in order to set up a practice.