This site is intended for health professionals only

Survey finds key information lacking for popular herbal medicines

Safety information is lacking for over 90% of herbal medicines commonly bought by patients, according to new research warning of a risk of dangerous interactions with drugs prescribed by GPs.

St John's wort, Asian ginseng, Echinacea, garlic and ginkgo are herbal medicines that have side effects when combined with prescribed drugs. St John's wort, for example, can reduce the effectiveness of the contraceptive pill, may also affect warfarin and Asian ginseng is not suitable for people with diabetes.

A study looked at 68 preparations of these medicines and rated them on whether they provided safety information and, if provided, whether it was complete and accurate regarding precautions, interactions with other drugs, and side effects.

Information was provided with 13% of the products but only three contained an acceptable amount of safety information guided by the US National Center for Complementary and Alternative Medicine.

Professor Theo Raynor, a professor of pharmacy practice at University of Leeds, stressed that it was important GPs were aware of herbal remedies that could cause dangerous drug interactions.

‘This study has shown that, among five herbal products commonly purchased over the counter in the UK, most contained little or no information regarding what to check for in order to avoid harm before using the product.'

'This study provides evidence supporting the need to strengthen regulation of herbal medicines in the EU.'

'Consumers should be encouraged to tell their healthcare practitioners about any use of herbal products, and practitioners should consider initiating such discussions. This does not, however, take away the necessity for accurate and complete written information about precautions, interactions and side effects to be provided to consumers when they buy herbal products.'

The study was published online in BMC Medicine.