Herbal remedies and clinical biochemistry.

The use of herbal products in the UK is increasing, and over-the-counter herbal supplements are perceived by the public as 'safe' and 'harmless'. Although the majority of them are safe, some herbal medicines carry risks. Heavy metal contamination, adulteration with Western pharmaceuticals and inclusion of prohibited animal and plant ingredients are regularly reported in ethnic medicines. Other herbs are hepato- or nephrotoxic and some interact with prescription medicines. Doctors should be made aware of the need to take a herbal as well as a drug history, and the clinical laboratory has a role in helping understanding of how herbal products may affect laboratory tests and in suggesting relevant lines of investigation in patients whose symptoms may be linked to the use of herbal products.