green-tea and Jantoven Interactions

Interactions between green-tea(green tea) and Jantoven (warfarin)

warfarin and green tea (Minor Drug-Drug)

Green tea in large amounts may antagonize the pharmacologic effect of warfarin and other related anticoagulants. Dried green tea leaves have been found to contain substantial amounts of vitamin K. Although brewed green tea is generally not considered a significant source of the vitamin, large amounts may contain sufficient vitamin K to interfere with the activity of some anticoagulants. A substantial decrease in the INR has been reported in a patient treated with warfarin after he began consuming large quantities (0.5 to 1 gallon daily) of green tea. While there is no need for patients treated with warfarin or related agents to avoid green tea, they should be advised that large quantities may diminish the effectiveness of their anticoagulation therapy.