MRCGP exam update - Are herbal medicines safe?

Current situation

- Legally, herbal products are classified as food supplements and they are widely available from health food shops and chemists.

- Worldwide several thousand different plants are being used for medicinal purposes.

Also conventional western medicine uses drugs derived from plants such as digoxin, morphine and vincristine.

What is the evidence?

- For most herbal treatments good trials of efficacy are lacking, and conducting them would be expensive. Without evidence of efficacy it is hard to judge the safety of herbal medicines, not least because the risk of an adverse effect that might be acceptable for an effective treatment will be unacceptable for an ineffective one (BMJ 2005; 331: 62).

- One study found that most pharmaceutical and herbal companies had never conducted research regarding herb-drug interactions (Arch Int Med 2003; 163: 1,371).

- Saw palmetto has shown no benefit over placebo for the symptoms of benign prostatic hyperplasia, according to a double-blind, randomised trial, despite over two million US men taking it (NEJM 2006; 354: 557).

- The herbal remedy black cohosh has been shown to offer little relief from menopausal hot flushes. The researchers found no differences between women using herbal products and placebo in the frequency or intensity of the hot flushes (Maturitas 2005; 16: 134).

- Two herbal remedies used to treat irritable bowel syndrome do not stand the scrutiny of a randomised controlled trial. Curcuma xanthorrizha and Fumaria officinalis are used by patients who are looking for alternative medicine. Neither, however, performed any better than placebo (Scan J Gastro 2005; 40: 936).

Primary care implications

- Many patients still believe that doctors prescribe too many medicines.

Some also suspect that medicines are either addictive or lose some of the efficacy with regular use.

- Patients question the safety of medicines. They perceive treatments containing herbal agents to be natural and safe.

- In the UK the Medicines and Healthcare products Regulatory Agency (MHRA) is consulting on a proposal for a Herbal Medicines Advisory Committee.

- The European Traditional Herbal Medicinal Products Directive, effective in the UK since October 2005, demands compulsory registration of all manufactured, pre-packaged unlicensed herbal products.

- All manufactured herbal medicines must meet specific standards of safety and quality, show either efficacy or long-standing traditional use, and be accompanied by the necessary information for the product to be used safely.

Useful websites

www.mhra.gov.uk - Medicines and Healthcare Advisory Committee

- Dr Louise Newson is a GP in the West Midlands and author of 'Hot Topics for MRCGP and General Practitioners', PasTest 2004

KEY POINTS
- The use of herbal medicines is on the increase.
- More research needs to be done regarding the efficacy of herbal
medicines.
- GPs should be aware of any herbal medicines their patients may be
taking.

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