Millions of people use it to deal with illnesses ranging from asthma to migraine. Prince Charles believes it is the answer to many of the evils of modern life. But now Britain's first professor of complementary medicine, Edzard Ernst of Exeter University, has denounced homeopathy as ineffective.

'Homeopathic remedies don't work,' he told The Observer. 'Study after study has shown it is simply the purest form of placebo. You may as well take a glass of water than a homeopathic medicine.' Nor is Ernst's disdain confined to homeopathy. Chiropractic, which involves spine manipulation to treat illnesses, and the laying on of hands to 'cure' patients, are equally invalid, he says.

Not surprisingly, his views and his studies have provoked furious reactions. Chiropractors and homeopaths have written in droves to Exeter to denounce him. But now the scourge of alternative medicine says he is going to have to quit because Exeter will no longer support him or his department. 'They have never provided me with the money they originally promised me. Now we have been told in no uncertain terms that this department is going to close.' The university denied the charge. 'Professor Ernst's department has enough money to go on for a couple of more years,' said a spokesman. 'We are still trying to raise cash. It is premature to talk of closure.'

Ernst's department was created in 1993 when Exeter was given £1.5 million by construction magnate Maurice Laing. When accepting these funds, Ernst said the university promised to raise the same amount again. 'They never did,' he added. Ernst, then a professor of rehabilitation medicine in Vienna, took the job to bring scientific rigour to the study of alternative medicines, an approach that has made him a highly controversial figure in the field. An example is provided by Ernst's study of arnica, given as a standard homeopathic treatment for bruising.

'We arranged for patients after surgery to be given arnica or a placebo,' he said. 'They didn't know which they were getting. It made no difference. They got better at the same rate, whether they got arnica or the placebo. And arnica is a classic homeopathic remedy. It doesn't work, however.'

In another study, Ernst got five homeopaths to examine children with asthma. 'Children are supposed to respond better than adults to homeopathy, and asthma is said to be particularly responsive to homeopathic treatments,' he said. 'However, again we found no evidence that homeopathy worked.'

Yet thousands of people swear by it. Britain has five homeopathic hospitals, which are funded by the NHS. 'The treatments do no good,' said Ernst. 'But the long interview - about an hour-and-a-half - carried out by an empathetic practitioner during diagnosis may explain why people report improvements in their health. However, that kind of attention cannot be afforded by the NHS.' The incredibly dilute solutions used by homeopaths also make no sense, he added. 'If it were true, we would have to tear up all our physics and chemistry textbooks.'

Nevertheless, Ernst insists that he is a supporter of complementary medicines. 'No other centre in the world has produced more positive results than we have to support complementary medicine,' he said. 'Herbal medicine, for instance, can do good. If I was mildly depressed, I think St John's wort would be a good treatment. It has fewer side-effects than Prozac. Acupuncture seems to work for some conditions and there are relaxing techniques, including hypnotherapy, that can be effective. These should not be used on their own, but as complements to standard medicines.'

Not surprisingly, Ernst has been attacked by chiropractors and homeopaths who passionately defend their techniques. The latter point to studies which they say show that most patients they treat are satisfied and cite an analysis in the Lancet of 89 trials in which their medicines were found to be effective. The Smallwood report, commissioned by Prince Charles, has called for more complementary medicines, particularly homeopathy, to be given on the NHS.

Ernst's opponents also claim some of his research methods are unethical. Once, a colleague pretended to be a pregnant mother and asked homeopaths and chiropractors if she should give the MMR vaccine to her child. Most said no. Ernst published a paper on these findings.

The British Chiropractic Association told the university it would be better served by an individual who was 'genuinely interested' in complementary medicine.

'I think my peers would prefer someone who didn't rock the boat,' said Ernst.

The 'other' treatments

Homeopathy Invented 250 years ago by a German doctor, Samuel Hahnemann, homeopathy is based on the idea that, if a particular drug or chemical causes a medical problem, it should also act as a cure, though only in an almost infinitely dilute state. There are about 3,000 registered homeopaths in the UK and 21 per cent of GPs offered a homeopathy service in 2001 compared with 17 per cent in 1995. Skin disease, irritable bowel syndrome and depression are among the ailments supposed to be improved by homeopathy.

Herbal medicine Plants or plant derivatives are used in herbal medicine to treat, prevent or cure various ailments. The approach has been used since 1500BC by the Egyptians. Today there are many branches, including Ayurveda, Chinese, Tibetan and Western herbal medicine. Popular remedies include echinacea, ginger, garlic, peppermint, feverfew, elderberry, goldenseal, St John's wort (below), ginseng and ginkgo. Consumers in Britain spend £126 million a year on herbal remedies to treat conditions such as constipation, diarrhoea and indigestion.