Interactions Between Herbal Medicines and Prescribed Drugs An Updated Systematic Review Angelo A. Izzo 1 and Edzard Ernst 2 1 Department of Experimental Pharmacology, University of Naples Federico II, Naples, Italy 2 Complementary Medicine, Peninsula Medical School, Universities of Exeter and Plymouth, Exeter, UK Contents Abstract ................................................................................ 1777 1. Systematic Review .................................................................... 1779 1.1 Methods ......................................................................... 1779 1.2 Results ........................................................................... 1779 2. Discussion............................................................................ 1779 2.1 Echinacea ....................................................................... 1779 2.2 Garlic ........................................................................... 1779 2.3 Ginkgo .......................................................................... 1786 2.4 Ginseng (Asian Ginseng) ........................................................... 1787 2.5 Kava ............................................................................ 1788 2.6 Saw Palmetto .................................................................... 1788 2.7 St John’s Wort .................................................................... 1788 2.7.1 Immunosuppressants ......................................................... 1789 2.7.2 Hormonal Therapy ........................................................... 1789 2.7.3 Cardiovascular Drugs ........................................................ 1790 2.7.4 Antiretrovirals Drugs .......................................................... 1790 2.7.5 Anticancer Drugs ............................................................ 1790 2.7.6 Drugs Acting on the CNS ..................................................... 1790 2.7.7 Drugs Acting on the Respiratory System ......................................... 1792 2.7.8 Hypoglycaemic Drugs........................................................ 1792 2.7.9 Antimicrobials ............................................................... 1792 2.7.10 Antimigraine Drugs ......................................................... 1792 2.7.11 Drugs Acting on the Gastrointestinal Tract ...................................... 1792 2.7.12 Summary of St John’s Wort Interactions ........................................ 1792 3. Limitations ........................................................................... 1793 4. Conclusions .......................................................................... 1793 Abstract The concomitant use of herbal medicines and pharmacotherapy is wide spread. We have reviewed the literature to determine the possible interactions between seven popular herbal medicines (ginkgo, St John’s wort, ginseng, garlic, echinacea, saw palmetto and kava) and conventional drugs. Literature searches were performed using MEDLINE, Cochrane Library and EMBASE and we identified 128 case reports or case series, and 80 clinical trials. REVIEW ARTICLE Drugs 2009; 69 (13): 1777-1798 0012-6667/09/0013-1777/$55.55/0 ª 2009 Adis Data Information BV. All rights reserved.