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Green Tea Extract Side Effects & Safety

This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Safe with Caution

Potential Side Effects

  • Hepatotoxicity risk — rare but serious liver injury reported with high-dose extracts (>800mg EGCG/day), especially on empty stomach; EFSA issued safety guidance
  • Caffeine-related effects (insomnia, anxiety, jitteriness) unless using decaffeinated extract
  • GI discomfort (nausea, stomach pain) especially on empty stomach
  • Iron absorption reduction — catechins chelate non-heme iron; separate from iron supplements by 2 hours

Drug & Supplement Interactions

  • Iron supplements — EGCG reduces non-heme iron absorption by up to 25%; take at different times
  • Stimulants and caffeine — additive stimulant effects if extract contains caffeine
  • Nadolol and other beta-blockers — green tea may reduce nadolol absorption by 85%
  • Warfarin — green tea contains vitamin K; large amounts may reduce anticoagulant effect
  • Hepatotoxic drugs — avoid combining high-dose GTE with other hepatotoxic medications

Maximum Dose

Do not exceed: Do not exceed 800mg EGCG daily; doses above this increase hepatotoxicity risk per EFSA safety assessment

Full Green Tea Extract Guide

References

  1. (). The effect of green tea on inflammatory mediators: a systematic review and meta-analysis of randomized clinical trials. Phytotherapy Research. DOI
  2. (). The effect of green tea supplementation on obesity: a systematic review and dose-response meta-analysis of randomized controlled trials. Phytotherapy Research. DOI
  3. (). Scientific opinion on the safety of green tea catechins. EFSA Journal. DOI