Herbal preparations can be problematic for a variety of reasons – but what role should pharmacists play?
Use of herbal medicines is increasing in Western countries despite the potential risks, say the authors of a comprehensive narrative review published in the MJA.
Mostly this is because consumers just don’t know about the risks involved.
Use of herbal and complementary products has been growing in the past two decades due to their ubiquity and accessibility, say the researchers from the University of Adelaide, and Murdoch and Curtin universities in WA.
“In Australia, the sale of herbal medicines is profitable and their use is advertised and strongly advocated in popular media, and is not balanced by package warnings or awareness campaigns about the risks and side effects,” they say.
“Access to traditional medicines does not require a prescription, and they are prominently advertised in the popular media.”
Consumers may also have a false belief that herbal preparations are “natural” and therefore risk-free.
But despite their growing use, there have been few recent investigations of the specific problems associated with the use of herbal medicines, with assessments of their safety relying on older studies.
Of concern is that while many Aussies are using complementary medicines including herbal products, more than half do not inform their healthcare providers and often use such products together with conventional medicines.
“A major area of concern is the potential interaction of herbal medicines with conventional drugs, both prescribed and over-the-counter products,” say the authors.
“Herbal medicines may enhance or reduce the effects of prescribed medications or elicit unpredictable idiosyncratic effects.”
Pharmaceutical agents are sometimes added to herbal products, even in those purchased in Australia.
Pharmaceuticals that have been detected in herbal products include: antibiotics, antihistamines, corticosteroids, aminopyrine, aspirin, bromhexine, chlordiazepoxide, diazepam, diclofenac, glibenclamide, hydrochlorothiazide, indomethacin, mefanamic acid, paracetamol, phenacetin, phenylbutazone and theophylline.
Toxic substances and contaminants including heavy metals, pesticides, herbicides, microorganisms, mycotoxins and insects have also been found in herbal preparations.
Reported adverse events include myocardial infarction, congestive heart failure, arrhythmia, hypotension, hypertension, arteritis, pericarditis, movement disorders, muscle weakness, stroke and seizures.
There have been reports of Cushing’s syndrome, aplastic anaemia, hypoglycaemia, renal failure, fatal hepatic failure, and lethal cardiac failure.
The PSA has reinforced its position that it does not support the sale of homeopathy products such as herbal medicines in pharmacy.
Pharmacists should be aware that there is potential for interactions between conventional or prescribed medicines and complementary medicines, it says.
Common herbal preparations known to have pharmacological interactions include St John’s wort, Asian ginseng, garlic, evening primrose and borage oils, dong quai, Devil’s claw, and dan shen.
“When discussing the use of complementary medicines with consumers, pharmacists must ensure that consumers are provided with the best available information about the current evidence for efficacy, as well as information on any potential side effects, drug interactions and risks of harm,” says the PSA.
“Pharmacists, as medicines and medication management experts, have a fundamental role in ensuring consumers have access to safe and effective medicines.”
PSA reminds pharmacists to consider available evidence for the use of complementary and herbal medicines before deciding to stock them in their pharmacy.
“In the event that a consumer chooses to use a product with limited evidence, the pharmacist must advise the consumer on the risks of rejecting or delaying treatments for which there is good evidence of safety and effectiveness.”
The MJA authors argue that due to the risks herbal medicines present to the Australian community, the TGA needs to adopt new auditing approaches and prosecute manufacturers who misrepresent the composition of herbal products.
“With more than one in 20 complementary medicines failing essential composition quality control in Australia, it is clear that more meaningful regulation of the sector is needed,” they say.
“How many more adverse drug reactions involving herbal products are needed before more attention is given to this important public health problem?”
Read the full MJA review here