NSTK · 01.2026Independent supplement reference
NutriStack
Edition 1.0Updated August 1, 2026

Supplement × Prescription·Evidence index

Green Tea Extract and Warfarin: what the published research says

PubMed indexes 6 records that name Green Tea Extract and Warfarin together, either in the title or in an interaction, co-administration, or pharmacokinetic context. Each one is listed below with its study design and, where the abstract states one, the authors’ own conclusion, quoted and linked. This page reports that literature. It does not tell you whether to combine them.

Read this first

An evidence index, not guidance.

Every statement below is attributed to a named, dated, linked source.

This page lists published research relevant to Green Tea Extract and Warfarin. It deliberately does not state whether the combination is safe, whether it interacts, in which direction, at what dose, or how far apart to take them.

The research

6 studies naming Green Tea Extract and Warfarin.

Strongest relevance first: papers naming both substances in the title, then human trials and systematic reviews.

Probable antagonism of warfarin by green tea.

The Annals of pharmacotherapy · 1999 · PMID 10332534

Case ReportsHuman subjects

“Warfarin is a highly effective oral anticoagulant, but it requires close monitoring to prevent complications. Patients receiving warfarin need to be routinely questioned about their intake of vitamin K-containing foods and beverages.”

Taylor et al. · Authors' conclusion

Names both Green Tea Extract and Warfarin in its title.

The combination of EGCG with warfarin reduces deep vein thrombosis in rabbits through modulating HIF-1α and VEGF via the PI3K/AKT and ERK1/2 signaling pathways.

Chinese journal of natural medicines · 2022 · PMID 36162953

Human subjects

“Furthermore, HIF-1α silencing significantly up-regulated cell apoptosis and ROS generation, and enhanced VEGF expression and the activation of the PI3K/AKT and ERK1/2 signaling pathways. In conclusion, our results indicate that EGCG combined with warfarin modifies HIF-1α and VEGF to prevent DVT in rabbits through anti-inflammation via the PI3K/AKT and ERK1/2 signaling pathways.”

Li et al. · From the abstract

Names both Green Tea Extract and Warfarin in its title.

Green tea may inhibit warfarin.

International journal of cardiology · 2007 · PMID 16757048

Letter

Names both Green Tea Extract and Warfarin in its title.

Warfarin and food, herbal or dietary supplement interactions: A systematic review.

British journal of clinical pharmacology · 2021 · PMID 32478963

Systematic ReviewHuman subjects

“While most food, herbs and supplements can be safely taken in moderation, healthcare professionals should be aware of the increased risk of bleeding when taking several food and herbs. These include Chinese wolfberry, chamomile tea, cannabis, cranberry, chitosan, green tea, Ginkgo biloba, ginger, spinach, St. John's Wort, sushi and smoking tobacco.”

Tan et al. · Authors' conclusion

Names Green Tea Extract and Warfarin together in an interaction, co-administration, or pharmacokinetic context.

Effect of herbal consumption on time in therapeutic range of warfarin therapy in patients with atrial fibrillation.

Journal of cardiovascular pharmacology · 2011 · PMID 21558883

Comparative StudyHuman subjects250 participants

“In conclusion, the patients with AF treated with warfarin had little knowledge about the potential interaction of herbal substances in foods with warfarin. The patients who consumed common herbs at least 4 times per week had suboptimal anticoagulation control with warfarin.”

Chan et al. · From the abstract

Names Green Tea Extract and Warfarin together in an interaction, co-administration, or pharmacokinetic context.

Limitations

What this evidence cannot tell you.

Search-based evidence indexes have real limits, and it is worth being explicit about them:

NutriStack

Track what you actually take.

NutriStack is a free iPhone app for organising a supplement routine: what you take, when, and what the published record says about it. Its exploratory interaction checker covers Green Tea Extract, Warfarin, and several hundred other substances.

The checker is a research and organisation tool, not a clinical decision aid, and its per-pair assessments are excluded from search until they pass claim-level review.

NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.