Cited by 802Complementary and Alternative Medicine StudiesPharmacogenetics and Drug MetabolismNatural Compound Pharmacology Studies

Interactions Between Herbal Medicines and Prescribed Drugs: An Updated Systematic Review

Izzo, Angelo A., Ernst, Edzard·2009·Drugs

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. Clinical trials indicate that St John's wort (Hypericum perforatum), via cytochrome P450 (CYP) and/or P-glycoprotein induction, reduces the plasma concentrations (and/or increases the clearance) of alprazolam, amitriptyline, atorvastatin, chlorzoxazone, ciclosporin, debrisoquine, digoxin, erythromycin, fexofenadine, gliclazide, imatinib, indinavir, irinotecan, ivabradine, mephenytoin, methadone, midazolam, nifedipine, omeprazole, oral contraceptives, quazepam, simvastatin, tacrolimus, talinolol, verapamil, voriconazole and warfarin. Case reports or case series suggest interactions of St John's wort with adrenergic vasopressors, anaesthetics, bupropion, buspirone, ciclosporin, eletriptan, loperamide, nefazodone, nevirapine, oral contraceptives, paroxetine, phenprocoumon, prednisone, sertraline, tacrolimus, theophylline, tibolone, tryptophan, venlafaxine and warfarin. Ginkgo (Ginkgo biloba) decreases the plasma concentrations of omeprazole, ritonavir and tolbutamide. Clinical cases indicate interactions of ginkgo with antiepileptics, aspirin (acetylsalicylic acid), diuretics, ibuprofen, risperidone, rofecoxib, trazodone and warfarin. Ginseng (Panax ginseng) may interact with phenelzine and warfarin. Kava (Piper methysticum) increases the clearance of chlorzoxazone (a CYP2E1 substrate) and may interact with alprazolam, levodopa and paroxetine. Garlic (Allium sativum) interacts with chlorpropamide, fluindione, ritonavir and warfarin; it also reduces plasma concentrations of chlorzoxazone (a CYP2E1 probe). Echinacea might affect the clearance of caffeine (a CYP1A2 probe) and midazolam (a CYP3A4 probe). No interactions have been reported for saw palmetto (Serenoa repens). Numerous interactions between herbal medicines and conventional drugs have been documented. While the significance of many interactions is uncertain, several interactions, particularly those with St John's wort, may have serious clinical consequences.

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Crossref · 10.2165/11317010-000000000-00000

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Authors
Izzo, A. A., & Ernst, E.
Affiliations
  • University of Naples Federico II (IT)
  • University of Exeter (GB)
Corresponding author
  • Izzo, Angelo A.
  • Ernst, Edzard
Venue
Drugs
Published
2009-09
Volume
69
Issue
13
Pages
1777-1798
ISSN
0012-6667 (ISSN-L)
OpenAlex
W1794469725
Cited by
801
References
247
Citations by year
2026: 43 · 2025: 35 · 2024: 14 · 2023: 28 · 2022: 35 · 2021: 26 · 2020: 42 · 2019: 43 · 2018: 35 · 2017: 41 · 2016: 32 · 2015: 34 · 2014: 68 · 2013: 61 · 2012: 69
FWCI
10.37
Type
journal article
Language
en
Open access
closed
Locations
  • Drugs (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Complementary and alternative medicine › Complementary and Alternative Medicine Studies
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Pharmacology › Pharmacogenetics and Drug Metabolism
  • Life Sciences › Agricultural and Biological Sciences › Plant Science › Natural Compound Pharmacology Studies
Keywords
herb-drug interactions, Hypericum perforatum, Ginkgo biloba, Panax ginseng, kava, garlic, Echinacea, saw palmetto, cytochrome P450 induction, P-glycoprotein, drug interactions
MeSH terms
Clinical Trials as Topic, Cytochrome P-450 Enzyme System, Humans, Herb-Drug Interactions

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