Evaluation of documented drug interactions and contraindications associated with herbs and dietary supplements: a systematic literature review.
OBJECTIVE
The use of herbs and dietary supplements (HDS) alone or concomitantly with medications can potentially increase the risk of adverse events experienced by the patients. This review aims to evaluate the documented HDS-drug interactions and contraindications.


METHODS
A structured literature review was conducted on PubMed, EMBASE, Cochrane Library, tertiary literature and Internet.


RESULTS
While 85 primary literatures, six books and two web sites were reviewed for a total of 1,491 unique pairs of HDS-drug interactions, 213 HDS entities and 509 medications were involved. HDS products containing St. John's Wort, magnesium, calcium, iron, ginkgo had the greatest number of documented interactions with medications. Warfarin, insulin, aspirin, digoxin, and ticlopidine had the greatest number of reported interactions with HDS. Medications affecting the central nervous system or cardiovascular system had more documented interactions with HDS. Of the 882 HDS-drug interactions being described its mechanism and severity, 42.3% were due to altered pharmacokinetics and 240 were described as major interactions. Of the 152 identified HDS contraindications, the most frequent involved gastrointestinal (16.4%), neurological (14.5%), and renal/genitourinary diseases (12.5%). Flaxseed, echinacea, and yohimbe had the largest number of documented contraindications.


CONCLUSIONS
Although HDS-drug interactions and contraindications primarily concerned a relatively small subset of commonly used medications and HDS entities, this review provides the summary to identify patients, HDS products, and medications that are more susceptible to HDS-drug interactions and contraindications. The findings would facilitate the health-care professionals to communicate these documented interactions and contraindications to their patients and/or caregivers thereby preventing serious adverse events and improving desired therapeutic outcomes.
School of Pharmacy and Graduate Institute, College of Pharmacy, China Medical University, Taichung, Taiwan.
H-H
HH
Tsai
H-W
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Lin
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Simon Pickard
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HY
Tsai
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Mahady
D000818:Animals; D002986:Clinical Trials as Topic; D000075202:Contraindications; D019587:Dietary Supplements / Q000009:adverse effects*; D004195:Disease Models, Animal; D041743:Herb-Drug Interactions; D006801:Humans; D028321:Plant Preparations; D051381:Rats; D012107:Research Design
D028321:Plant Preparations