Herb–drug interactions: Review and assessment of report reliability

Authors

  • Adriane Fugh-Berman,

    1. Department of Health Care Sciences, George Washington University of Medicine, 2150 Pennsylvania Avenue N.W. #2B417, Washington, D.C. 20037 (preferred mailing address: 1312 18th St. N.W. #500, Washington, D.C. 20036), USA and
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  • E. Ernst

    1. Department of Complementary Medicine, School of Postgraduate Medicine and Health Sciences, University of Exeter, 25 Victoria Park Road, Exeter EX2 4NT
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Professor E. Ernst, Department of Complementary Medicine, School of Postgraduate Medicine and Health Sciences, University of Exeter, 25 Victoria Park Road, Exeter EX2 4NT. Tel.:/Fax: −44-1392-424989; E-mail: E.Ernst@exeter.ac.uk

Abstract

Aims  The aim of this systematic review was to assess the published clinical evidence on interactions between herbal and conventional drugs.

Methods  Four electronic databases were searched for case reports, case series or clinical trials of such interactions. The data were extracted and validated using a scoring system for interaction probability.

Results  One hundred and eight cases of suspected interactions were found. 68.5% were classified as ‘unable to be evaluated’, 13% as ‘well-documented’ and 18.5% as ‘possible’ interactions. Warfarin was the most common drug (18 cases) and St John's wort the most common herb (54 cases) involved.

Conclusion  Herb–drug interactions undoubtedly do occur and may put individuals at risk. However our present knowledge is incomplete and more research is urgently needed.

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