Alternative remedies can be dangerous for children and could even be fatal, experts have warned.
Parents are sometimes misled into thinking they are 'more natural', with fewer side effects than conventional drugs, they say.
A study team from the Royal Children's Hospital in Melbourne, Australia, used data from 2001 to 2003 showing 39 separate incidents of side effects in children up to the age of 16.
It found that the deaths of four children could be blamed on parents failing to use conventional treatments for illness and using alternative medicines instead.
In 25 cases, the adverse effects were rated as severe, life-threatening or fatal, and in almost half of cases, including the four deaths, the patient was harmed by a failure to use conventional medicine.
One involved an eight-month-old admitted to hospital with malnutrition and septic shock following naturopathic treatment with a rice milk diet from the age of three months for constipation.
'Another death involved a ten-month-old with septic shock following treatment with homeopathic medicines and dietary restriction for chronic eczema,' said the report in the journal Archives of Disease in Childhood.
The third death was sudden in a child who had presented with multiple seizures. 'A number of different complementary and alternative medicine therapies had been used instead of anti-convulsant therapy due to concerns about potential drug side effects,' the report said.
The fourth death was of a child who needed blood-clotting drugs but was given complementary medicine instead.
The report said: 'Many of the adverse events associated with failure to use conventional medicine resulted from the family's belief in complementary and alternative medicine and determination to use it despite medical advice.'
Speaking in the Guardian, Professor Edzard Ernst, from the department of complementary medicine at Peninsula Medical School in Exeter, said parents must be very careful.
'The ethics of using alternative remedies in children are complex,' he added.
But Cristal Sumner, of the British Homeopathic Association, said: 'With millions in Britain using complementary medicines (CAM), this study only emphasises the importance of CAM being integrated into the healthcare system and delivered by statutorily regulated health professionals.
'Most of the risks from CAM come from the failure to responsibly integrate therapies appropriately rather than a direct risk from treatments.'
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