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A review of clinically significant interactions between medicines and green tea

Maya Radeva-Ilieva


Green tea intake for prevention and/or treatment of diseases is widespread worldwide. Green tea is known for its antioxidant, anti-inflammatory, anti-tumor effects, and others. Tea leaves contain various biologically active substances and their concomitant use with medicinal products carries the risk of potentially dangerous interactions. The aim of the present study was to assess the clinical significance of interactions that may occur after co-administration of drugs with green tea. A thorough review of the scientific literature was conducted and a number of studies, both in experimental animals and in humans that reported pharmacokinetic interactions with certain drugs were identified. Most authors suggest that the observed interactions are due to the ability of the green tea extract, as well as the contained catechins, mainly epigallocatechin-3-gallate (EGCG), to modulate the activity of some drug-metabolizing enzymes and transmembrane transporters. As a result, changes in plasma drug concentrations leading to an increased risk of toxic effects or reduced therapy effectiveness are observed. Drug interactions have also been observed after simultaneous intake of certain medications and caffeine, which is also present in tea leaves. In conclusion, concomitant use of drugs with green tea, EGCG or caffeine, in any form, may lead to clinically significant drug interactions and adverse patient outcomes.


drug interactions, pharmacokinetic, green tea, epigallocatechin-3-gallate (EGCG), caffeine

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