In the paper published in the Medical Journal of Australia, researchers cited a range of issues relating to the preparation of complementary medicines, including the presence of toxic chemicals, heavy metals and pesticides.
"Toxic side effects of herbal medicines used in traditional societies have typically not been reported, and this is often cited in favour of their safety. However, 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," said lead author Professor Roger Byard, Professor of Pathology at the University of Adelaide.
The review – by researchers from the University of Adelaide, Murdoch University and Curtin University – states more than half of those using complementary medicines (including herbal products) do not inform their doctors of use. Patients often use these products alongside conventional medications and with other herbal medications.
"Most of the time patients don’t recognise herbal products as a medicine, so it doesn’t come to mind when asked what medicines they are taking," added co-author Dr Ian Musgrave from the University's Discipline of Pharmacology.
"It can also be a situation of 'don’t ask, don’t tell' – medical doctors may not think to ask patients what herbal medicines they might be taking, so people don't think to mention it. The problem with this is that drug interactions are poorly recognised in herbs – not only can herbal medicines interact with traditional pharmaceutical medicines but also with other herbal medicines the patient may be using."
The authors say that due to the “light regulation” of the industry, the content and quality of herbal preparations are not as tightly controlled as standard pharmaceuticals.
However, CMA CEO Carl Gibson said Australia has some of the most stringent regulations in the world for herbal products, as it does for all complementary medicines on the Australian market.
“Products are required to be entered onto the Australian Register of Therapeutic Goods (ARTG) which is maintained by the regulator, the Therapeutic Goods Administration (TGA),” he said.
“Unless entered on the ARTG, these products cannot be legally imported, exported, manufactured, or supplied to consumers in Australia.”
He stressed that many of claims made in the paper concerned products bought online from overseas – not those manufactured and sold in Australia.
“Products that are medicinal in nature but not listed on the ARTG may not have been made under GMP principles, and may not meet the quality and safety standards expected by Australian consumers.
“Concerns raised by the authors, such as adulteration with pharmaceutical agents, inadequate processing and the presence of toxic substances, have been known to affect products purchased online from overseas, which are not subject to the same regulations as those enforced in Australia.”
CMA says the Australian regulatory environment mandates that the following occur in the manufacture of complementary medicines available on the Australian market:
- Only utilise ingredients assessed as safe and allowed at safe levels by the TGA.
- The TGA mandates verification testing of all raw materials before a product is manufactured, which provides assurance to Australian consumers that they receive what's stated on the label.
- Batch testing of finished products (tablets /capsules) verifies consistency and quality of the active ingredients within the label claim.
- Stability studies ensure that the product remains potent and safe throughout its shelf life.
- Product quality reviews ensure that quality data is aggregated and tracked over time, allowing the industry to identify and act on any emerging trends.
- Adverse events are rigorously captured and monitored by the TGA so that any emerging issues can be identified and addressed promptly.
But Dr Musgrave said far more testing was required to protect consumers.
"Any sensible way to overcome these issues will involve more effort: more testing, more documentation, and this will naturally incur more costs for industry.
“There will be a reluctance from industry to do this, but while they claim that for thousands of years they have been using herbal products without such tests, the potential risks to human health mean that there is due cause for reasonable, scientifically rigorous testing."