Herbal medicines put into context

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Taken from the BMJ:

http://bmj.bmjjournals.com/cgi/content/full/327/7420/881?etoc

 

Their use entails risks, but probably fewer than with synthetic

drugs

 

Recent reviews have rightly alerted us to the risk associated with

herbal medicines.1 This is necessary and important. But the more

important question probably is—do the risks of herbal benefits

outweigh their potential for harm? Therefore I will try to put

herbal medicines into context and consider the benefit they might

bring.

 

The potential benefits of herbal medicines could lie in their high

acceptance by patients, efficacy, relative safety, and relatively

low costs. Patients worldwide seem to have adopted herbal medicines

in a major way. Survey data from the United Kingdom show that herbal

medicine has been tried by about 30% of the British population.2 The

associated out of pocket expenditure was estimated to amount to £31m

(US$47.7m; €45m) in the United Kingdom2 and £1.3bn in Germany.3

Herbal medicines are used predominantly for minor and self limiting

indications, with respiratory tract infections heading the list.3

But even for those conditions the remarkable acceptance of herbal

medicines can be a good thing only if they can be shown to do more

good than harm at reasonable cost.

 

The efficacy of herbal medicines has been tested in hundreds of

clinical trials, and it is wrong to say that they are all of

inferior methodological quality. But this volume of data is still

small considering the multitude of herbal medicines—worldwide

several thousand different plants are being used for medicinal

purposes.4 A recent overview included 23 systematic reviews of

rigorous trials of herbal medicines.5 Eleven came to a positive

conclusion, nine yielded promising but not convincing results, and

three were negative. The relative paucity of rigorous clinical

trials is mostly due to the fact that, compared with the

pharmaceutical sector, the herbal industry is small and can rarely

afford the considerable expense of a clinical trial. Sadly the

traditional use directive, which sets out to harmonise the

registration of herbal medicines in the European Union,6 lacks any

incentive for companies to invest further into research. Public

funds are only very rarely dedicated to research in this area.7

 

Even though herbal medicines are not devoid of risk,1 they could

still be safer than synthetic drugs. Between 1968 and 1997, the

World Health Organization's monitoring centre collected 8985 reports

of adverse events associated with herbal medicines from 55

countries.8 Although this number may seem impressively high, it

amounts to only a tiny fraction of adverse events associated with

conventional drugs held in the same database.8 However, the relative

paucity could also be due to a relatively higher level of

underreporting. More conclusive evidence on the relative risks of

herbal medicine versus synthetic drugs is scarce. Linde et al showed

that the herbal antidepressant St John's wort has only about half

the rate of adverse effects compared with conventional

antidepressants.9 Kava, an effective herbal anxiolytic,10 has

recently been banned in several countries, including the United

Kingdom, because of the suspicion that, in rare cases, it causes

hepatotoxicity. None the less, preliminary data indicate that it

probably is still safer than benzodiazepines.11 At present the

relative safety of herbal medicines is undefinable, but many of the

existing data indicate that adverse events, particularly serious

ones, occur less often than with prescription drugs.4

 

A further strength of herbal medicines is that they are inexpensive,

at least this is what the " herbal lobby " wants us to believe. The

truth, however, is that almost no conclusive cost evaluation studies

are available.12 Many, but by no means all, herbal medicines are

inexpensive to buy; the potential for cost savings by using more

herbal medicines could therefore be substantial—at present, however,

we simply cannot be sure.

 

Thus the evidence on herbal medicines is incomplete, complex, and

confusing. They are certainly associated with both risks1 and

benefits.4 As more and more people try herbal medicines, the

pressure increases on healthcare professionals to be well informed

about the subject, and on researchers to fill the many and somewhat

embarrassing gaps in our current knowledge. Failing to do (and fund)

this work would, in my view, constitute the true risk associated

with herbal medicines.

 

E Ernst, director

 

Complementary Medicine, Peninsula Medical School, Universities of

Exeter and Plymouth, Exeter EX2 4NT (Edzard.Ernst)

 

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Competing interests: EE's unit has received research fellowships

from herbal manufacturers and retailers: Lichtwer UK, Pharmaton

Switzerland, and Boots UK. Financial support for other research

projects was also received from Schwabe Germany and Novogen

Australia.

 

References

 

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Medizin. Gesundheitsberichtserstattung des Bunds 2000;9: 1-37.

Ernst E, Pittler MH, Stevinson C, White AR, Eisenberg D. The desktop

guide to complementary and alternative medicine. Edinburgh: Mosby,

2001.

Ernst E. Herbal medicinal products: an overview of systematic

reviews and meta-analyses. Perfusion 2001;14: 398-404.[iSI]

Barnes J. Quality and safety at heart of new herbals directive.

Pharm J 2003;270: 201-2.

Ernst E, Wider B. Medical research charities should fund more

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Farah MH, Edwards R. International monitoring of adverse health

effects associated with herbal medicines. Pharmacoepidemiol Drug

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Linde K, Ramirez G, Mulrow CD, Pauls A, Weidenhammeer W, Melchart D.

St John's wort for depression—an overview and meta-analysis of

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Text]

Pittler MH, Ernst E. Kava extract for treating anxiety. Cochrane

Database Syst Rev 2003;(1): CD003383 [GenBank] .

Schulze J, Raasch W, Siegers CP. Toxicity of kava pyrones, drug

safety and precautions—a case study. Phytomedicine 2003;10 Suppl 4:

68-73.[iSI][Medline]

White AR, Ernst E. Economic analysis of complementary medicine a

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[Medline]

 

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