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Last Updated: 2 years ago

Possible Interaction: Marijuana and Warfarin



Research Papers that Mention the Interaction

Several case reports show cannabis may inhibit the metabolism of warfarin because of CYP2C9 interactions, resulting in increased plasma concentrations, increased international normalized ratio, and risk of bleeding.
Journal of clinical pharmacology  •  2019  |  View Paper
Some of them receive medications with known potential negative interactions with cannabis , such as THC-mediated increase in bleeding time in patients using warfarin (10).
Annals of Internal Medicine  •  2019  |  View Paper
Until further data are available, we suggest patients receiving warfarin be warned against cannabis use.
Basic & clinical pharmacology & toxicology  •  2019  |  View Paper
Discussion: The elevation in INR can be explained by the inhibition of CYP2C9 by cannabis use causing decreased metabolism of warfarin.
The INR dropped below 4 upon discontinuation of cannabis with dose adjustments to warfarin.
Journal of pharmacy practice  •  2019  |  View Paper
Discussion: Marijuana may increase warfarin anticoagulant effect by inhibiting its metabolism, and to a lesser extent, displacing warfarin from protein-binding sites.
He was counseled by the pharmacist on the potential interaction of warfarin and marijuana.
The Annals of pharmacotherapy  •  2009  |  View Paper
Among thirty-eight herbs, Cannabis , Chamomile, Cranberry, Garlic, Ginkgo, Grapefruit, Lycium, Red clover, and St. John's wort were evaluated to have major severity interaction with warfarin.
Evidence-based complementary and alternative medicine : eCAM  •  2014  |  View Paper