Others believe that alternative medicine is seeped in bad science and is practised by charlatans or the deluded.

In response, practitioners of alternative medicine are using the conventional medical establishment's own weapons of clinical trials and peer-reviewed studies to undermine its wall of scepticism.

The results have, in some cases, rocked the preconceived notions of many doctors, with more papers showing the success of therapies such as homeopathy and herbal medicine.

Homeopathy success

Researchers in Holland who were looking into the potential of homeopathy showed earlier this year that an infinitesimal quantity of arsenic shaken in several dilutions of water may cure diarrhoea.

And last November, clinical tests in Italy showed that a Chinese remedy for breech births - which involves burning a herb at the toe of a pregnant woman - actually works.

But there is still a long way to go before there is enough evidence to persuade everyone - especially as the efficiency of many remedies is based largely on anecdotal evidence.

Best bet

The gold standard of modern western medical research is the randomised controlled trial.

Acupuncture is one of the techniques with a growing base of evidence

Once a treatment has been shown to be safe, these trials look at whether or not it actually works.

One group of subjects is given a medicine with the active ingredient, while another is given dummy preparations - placebos. Neither group knows which they are getting.

So far, several such trials have shown promising results for alternative therapies - 29 trials have shown that acupuncture can reduce nausea after operations and three have shown that homeopathic remedies can help subdue hayfever.

Difficulties in establishing reliability

However, some researchers put the efficiency of herbal remedies and homeopathic medicines down to the placebo effect - in which patients' health improves after a dummy treatment because of their belief that they have received a proper medicine - and this adds to the difficulty of conducting a reliable study.

Dr Jonathan Monckton is director of the UK Research Council for Complementary Medicine, an independent charity that is trying to build a database to point people in the direction of reliable evidence on the subject.

He said establishing the usefulness of alternative therapies was a question of applying conventional standards to unconventional treatments.

However, it was important not to overlook people's own experiences, and scientists would have to strike a balance between clinical and anecdotal evidence when assessing a treatment's use, he said.

Safety fears

Although there are fears that without proper evidence some of treatments could do more harm than good, the main dangers are inappropriate use of therapies and practitioners ignoring conventional medicine when it was necessary.

The danger lies not so much with the herb as with the practitioner in some cases

"Just because it's natural doesn't mean it's safe - there are dangers of using acupuncture needles inappropriately, and there are dangers in using Chinese herbs that have hypoxins in them that will damage your liver, but there are also dangers in conventional medicine," Dr Monckton said.

In August the UK Government banned a herb used in Chinese medicine, after two patients fell ill having taken Aristolochia.

It had been used instead of harmless ingredients with a similar name in Chinese.

In May, Chinese and British doctors set up a centre to test the safety of herbal medicines, and this will add to the ever increasing base of knowledge on the safety and effectiveness of alternatives.

Lives at risk

The other danger - of using alternative therapies instead of conventional medicine - was highlighted by a survey of Internet health practitioners.

The researchers sent a number of "cyberdocs" descriptions of a condition and asked for advice. The correct advice was that the patient should seek immediate medical attention or else they might die.

One cyberdoc recommended "two bowel movements" or "two apples a day", and "Red Clover and Dandelion", which they offered to sell the patient.

Another recommended homeopathic medicine and vitamin C and charged $25 for the advice.

Growth area

"The exclusion of conventional treatment is the danger in these cases, not the therapy itself," Dr Monckton said.

"It's the greatest gift a therapist can have - to know when he doesn't know and refer to a different authority."