Review documents potentially harmful herb-drug interactions

Reactions 1427 - 10 Nov 2012

Review documents potentiallyharmful herb-drug interactions

A systematic literature review published in theInternational Journal of Clinical Practice provides acomprehensive summary of evidence on documentedinteractions between herbal remedies/dietarysupplements (HDS) and conventional medicines.1

Using data from primary literature, books andwebsites, researchers from Taiwan and the US identifieda total of 1491 unique pairs of HDS-drug interactions,featuring 213 different HDS entities and 509 differentmedications. The most commonly cited HDS productsincluded St. John’s wort, magnesium, calcium, iron andginkgo, while the most commonly cited conventionalmedications were warfarin, insulin, aspirin, digoxin andticlopidine. In general, herbal remedies were more likelyto have documented drug interactions than other dietarysupplements, while more than half of the documentedinteractions involved either a CNS drug, a cardiovasculardrug or an anti-infective. A total of 152 HDScontraindications were also identified, with flaxseed,echinacea and yohimbe having the largest number ofdocumented contraindications.

The researchers suggest that, while these findingsconcern a relatively small subset of commonly usedmedications and HDS entities, the information shouldhelp healthcare professionals communicate theseinteractions and contraindications to patients andcaregivers. In an accompanying editorial, ProfessorEdzard Ernst of the University of Exeter comments thatthe prevailing attitude among healthcare professionalsneeds to change.2 "As supplements are typically notprescribed, many doctors seem to have no interest indrug-supplement interactions," Ernst exclaims. "We haveto become vigilant and finally agree to monitor thissector adequately; each individual doctor can contributeto this process by routinely including questions aboutalternative medicine use in their medical history taking."1. Tsai H-H, et al. Evaluation of documented drug interactions and

contraindications associated with herbs and dietary supplements: a systematicliterature review. International Journal of Clinical Practice 66: 1056-1078, No.11, 1 Nov 2012. Available from: URL: http://dx.doi.org/10.1111/j.1742-1241.2012.03008.x.

2. Ernst E. Interactions between drugs and supplements: the tip of an iceberg?International Journal of Clinical Practice 66: 1017-1020, No. 11, 1 Nov 2012.Available from: URL: http://dx.doi.org/10.1111/ijcp.12007.

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Reactions 10 Nov 2012 No. 14270114-9954/10/1427-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved