A study published in the Medical Journal of Australia has found some traditional herbal medicines contain toxic pesticides and heavy metals.
There are calls for greater quality control of herbal medicines sold in Australia over concerns some potentially "toxic" products are putting people's health at risk.
A review published in the Medical Journal of Australia has found that some traditional herbal preparations contain chemicals from both animals and plants, as well as heavy metals and pesticides.
Lead author Roger Byard, Professor of Pathology at the University of Adelaide, says the "toxic" side effects of herbal medicines have typically gone unreported because of a "mistaken belief" that 'natural' means 'safe'.
Prof Byard says a significant number of traditional herbal medicines do not comply with Australian regulations and tighter controls are needed.
"The lack of systematic observation has meant that even serious adverse reactions, such as the kidney failure and liver damage caused by some plant species, have gone unrecognised until recently," he said.
The review also found more than half of the nearly 70 per cent of Australians who use herbal products don't inform their doctors.
Dr Ian Musgrave from the University of Discipline of Pharmacology says this is problematic.
"Not only can herbal medicines interact with traditional pharmaceutical medicines but also with other herbal medicines the patient may be using."
The authors of the paper say there is a clear case for more scientifically rigorous testing of herbal medicines, given their widespread use.
"We feel it would be appropriate for the Therapeutic Goods Administration to require manufacturers to have samples independently tested before placing them on the market," said Prof Byard.
"Legal action should be considered in cases of non-compliance with applicable regulations, and preparations containing illegal substances should be banned."