A report in the respected medical journal The Lancet said that patients treated with homeopathy fared no better than those treated with a dummy, "placebo" therapy. The article will add to the debate over whether complementary therapies should be provided on the health service.
Researchers from the University of Berne in Switzerland studied the results of 110 trials involving homeopathy and placebo treatments for a range of problems, from respiratory infections to post-surgical pain relief.
They also looked at 110 trials that used conventional medicine against placebo treatments.
While small trials that were considered low quality showed some benefit for homeopathy over placebo, there was no difference between the two in higher quality, larger trials. But, the benefits of conventional medicine were seen over all the studies.
The study concluded: "When the analysis was restricted to large trials of high quality there was no convincing evidence that homeopathy was superior to placebo, whereas for conventional medicine an important effect remained."
This suggests that homeopathy works if you believe in it, according to Professor Matthias Egger, of Berne University. "Our study powerfully illustrates the interplay and cumulative effect of different sources of bias," he said. "To prove a negative is impossible, but we have shown that the effects seen in placebo-controlled trials of homeopathy are compatible with the placebo-hypothesis."
Homeopathy was developed 250 years ago by Samuel Hahnemann, a German doctor who was concerned about the lack of effectiveness and the harm caused by traditional treatments. It is based on the theory that "less is more" - that diluting a drug makes it stronger, rather than weaker. The formulas used are based on the theory that even when a remedy is diluted to the point where no molecules are left, the water will contain energy and retain the "memory" of what it was once in contact with.
While some doctors believe it can help patients, others are highly sceptical. But scientists are not ruling out the prospect that there is room for both approaches in modern medicine.
Jan Vandenbroucke of the Leiden University Medical Centre in the Netherlands, said: "Science is an intrinsically human affair. When new theories are created and new evidence sought, judgement will retain a subjective element."
But The Lancet's editorial was scathing about homeopathy. It commented: "Doctors need to be bold and honest with their patients about homeopathy's lack of benefit, and with themselves about the failings of modern medicine to address patients' needs for personalised care."
Other studies have also questioned the benefits of complementary therapies such as acupuncture. But advocates of such therapies say that the methods used in clinical trials do not allow the benefits of alternative medicine to shine through.
There are now more than 47,000 practitioners of alternative medicine in the UK - more than the number of GPs.
Despite suspicion from some quarters of the medical establishment, many family doctors are embracing alternative therapies, with some practices now offering acupuncture and homeopathy within their surgeries.
The Prince of Wales, a supporter of complementary medicine, has commissioned a report on its benefits which he hopes will encourage the Government to fund more treatment on the NHS. The report is expected to claim that providing alternative therapies could save the health service up to £3.5bn in drugs bills.
Britons currently spend £130m a year on complementary treatments, such as acupuncture, herbalism and reflexology. It is estimated that this will pass £200m in the next four years.
Treating like with like
The market value of homeopathic remedies is estimated at £32m and is rapidly growing. Homeopathy is based on treating "like with like", so to cure a headache patients would be treated with a remedy that causes headaches.
Pre-menstrual tension: Diluted venom from the snake Lachesis muta muta is used to treat PMT and period pains. It can also be used to treat circulatory problems, varicose veins, angina, throat problems, headaches, nosebleeds, boils and disorders of the nervous system.
Backache: Arnica is useful to treat injuries and pain to soft tissue and muscles. As well as being ingested, ointment can be applied. It is also used to alleviate pain from arthritis, burns and ulcers; and to treat eczema and acne.
Headache: Bryonia is used to treat headaches when the person's symptoms are accompanied by irritability and does not want to move. Made from the fresh root of a climbing perennial plant, it is used particularly when the headache is left-sided or aggravated by coughing. Also used for bronchitis and chickenpox.Reuse content