A Tauranga-based medical researcher is calling on doctors not to practise homeopathy or refer their patients to homeopaths.

In a letter to the New Zealand Medical Journal, Professor Shaun Holt and other senior researchers from New Zealand and the United Kingdom say "practising homeopathy or endorsing it by referring patients is not consistent with the ethical or regulatory requirements of practising medicine".

Homeopathy is a form of alternative medicine in which practitioners treat patients using highly diluted preparations believed to cause healthy people to exhibit symptoms similar to those exhibited by the patient.

One in eight New Zealand GPs practises homeopathy or refers patients to homeopaths.

The letter was triggered by the recently released Medical Council of New Zealand statement on complementary and alternative medicine, which informed doctors of the standards of practice that were expected of them.

The statement said doctors must inform patients on the nature of alternative treatments they offered, the extent to which they were consistent with conventional theories of medicine, whether they had the support of the majority of doctors, and their likely effectiveness according to peer-reviewed medical publications.

Prof Holt cited a few examples of homeopathic products:

"Berlin Wall" - consists of dust from the Berlin Wall, diluted until none remains, sold to people to help them stop feeling repressed;

"Saturn" - light from a telescope aimed at the planet Saturn is focused on sugar, which is then diluted many times and given to people for allergies, amongst other things:

"Arsenic" - diluted until virtually none remained, then used to treat a range of symptoms including insomnia and obsessive-compulsive disorder.

Although homeopathic products did no harm, as they did not contain any active ingredients, there could be serious problems when people used them instead of real medicines, Prof Holt said.

However Tauranga-based Susanna Shelton, co-president of the New Zealand Council of Homeopaths, said homeopathy had been safely practised around the world for 200 years.

She said homeopathy was low risk as the solutions used were highly diluted.

Mrs Shelton said homeopathy was a complementary, alternative medicine (CAM) used by registered homeopaths, general practitioners and midwives in the Western Bay and across New Zealand, and Prof Holt's claims were "unprofessional and unethical" to a profession that was well established and committed to people's wellness.

"I think it's very unprofessional for Holt to question his colleagues who choose to use homeopathy, especially if they've trained and are a registered practitioner.

"[Homeopathy] is not a new concept, it's been around for 200 years and just because Holt doesn't understand how it works doesn't mean it doesn't work."

Mrs Shelton said homeopathy was an effective complementary or alternative treatment option that had a significant following in the Western Bay.