Australasian Science: Australia's authority on science since 1938

Deadly Concerns Over Herbal Medicines

image of Professor Roger Byard

Professor Roger Byard, Photo: The University of Adelaide

By Roger W. Byard

Just how safe are herbal medicines, and how well are we evaluating their possible contribution to illness and death?

While there is no doubt that some pharmaceutical drugs carry significant risks of morbidity and sometimes mortality, a recent review of traditional herbal medicines has shown that “natural” does not always equate with “safe”. Published in the American Academy of Forensic Sciences Journal ofForensic Sciences, my review dealt withpotentially harmful effects and interactionsof herbal medicines that had been published in the international scientificliterature.

Although there are many time-honoured traditions of herbal medicine – particularly in India, China and otherparts of Asia – the world has changedand we are no longer dealing with herbal medicines based in a village context.Herbal medicine has become part of theglobal marketplace, and as such it is sometimes difficult to know where a particular medicine may have come from, what it may be composed of and what other ingredients or contaminants may be present.

Issues that have arisen around the world with Asian herbal supplies include contamination with heavy metals such as mercury and lead, the substitution of expensive herbs for cheaper ones that are sometimes more toxic, and the addition of standard pharmaceutical drugs such as steroids, antihistamines and anti-epileptics.

In addition, there have been well-documented interactions between certain herbs and prescription medications. It is the latter two issues that are of particular concern.

When a person dies suddenly andunexpectedly in Australia, their death isreported to the State Coroner who willdetermine whether an autopsy is necessaryto ascertain the cause of death. Thepathologist performing the autopsy relieson information provided by investigatingpolice officers at the death scene, and thisoften includes a list of prescribed medications.

If there is concern about a possible drug interaction, toxicological testing will be performed. Unfortunately this information rarely, if ever, includes herbal remedies.

Herbs such as St Johns Wort may reduce the effect of warfarin, a blood-thinning medication designed to prevent clotting. If a person taking warfarin dies from a blood clot in the lungs or brain, the conclusion is usually that this has happened despite appropriate therapy. The possible role of St Johns Wort would rarely be considered.

Similarly, death from a bleeding peptic ulcer would not usually raise the possibility of occult steroid or anti-inflammatory therapy administered via an apparently benign herbal mix.

Other problems with herbal preparations are that they may alter laboratory test results and also predispose subjects tobleeding problems. It is for this reason that the American College of Anesthesiologists recommends that herbal medicines should be stopped for at least 2 weeks before any surgical operation.

There is no doubt that many people inAustralia who are very committed toherbal medicines feel that there are veryreal benefits from their use. However,given the potential risks for interactionwith standard drugs and of drug additivesin unregulated preparations, thequestion to ask is how much have herbalpreparations contributed to morbidityand mortality?

As it is not standard practice to checkfor herbal medicines in medical andforensic evaluations, and as toxicologicaltesting for organic molecules is very difficult,the rather disturbing conclusionappears to be that we just do not know.

This represents a very worrying gapin our understanding of illness and in thepossible interactions that substances thatmany of us are taking may have.Continued research into the potentialproblems of herbal medicine is obviouslyneeded, in addition to a requirement forlabelling of all herbal substances, so thatconsumers will have a clear understandingof exactly what they are taking.

Professor Roger Byard is a senior forensic pathologist and Professor of Pathology at the University of Adelaide. He has had an interest in factors contributing to sudden death for a number of years. conScience is a column for Australians to express forthright views on national issues. Views expressed are those of the author.