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  5. Warfarin and Green Tea

INTERACTION STATUS
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Warfarin
Green Tea
Clinical Summary

Green tea contains vitamin K, which can interfere with warfarin's anticoagulant effects, potentially leading to fluctuations in blood clotting control.

Important Considerations

Keep green tea intake consistent to avoid INR fluctuations.

Green tea has moderate vitamin K content; excessive amounts (>4 cups/day) may pose higher risk.

Monitor INR closely if starting, stopping, or changing consumption levels.

Always discuss herbal tea use with a pharmacist or doctor before incorporating into routine.

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Medical Analysis
Mechanism

Warfarin works by inhibiting the synthesis of vitamin K-dependent clotting factors (II, VII, IX, X). Green tea, particularly its leaves, contains vitamin K, which can antagonize warfarin's action by providing additional substrate for clotting factor production, thereby reducing the drug's efficacy and potentially lowering INR levels.

Clinical Impact & Risks

Inconsistent green tea consumption may cause variable INR levels, increasing the risk of thromboembolism if INR decreases too much, or bleeding if it increases unexpectedly; moderate intake is generally low-risk but can still affect stability in sensitive patients.

Management & Recommendations

Advise patients to maintain consistent green tea consumption and avoid sudden changes in intake; regular INR monitoring is recommended, especially with alterations in diet; consult a healthcare provider for personalized advice on dietary habits while on warfarin.

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The content on SafeTo is for informational purposes only and does not constitute medical, veterinary, or professional advice. Always consult with a qualified professional for specific concerns.

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