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Green Tea Extract (EGCG) 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: Generally Safe

Potential Side Effects

  • Nausea on an empty stomach
  • Insomnia if caffeine-containing and taken late in the day
  • Rare hepatotoxicity at very high doses (>800 mg EGCG/day) — take with food to reduce risk
  • Iron absorption interference — separate from iron-rich meals

Drug & Supplement Interactions

  • Iron supplements — EGCG chelates iron and reduces absorption; separate by 2+ hours
  • Stimulant medications — additive effects if caffeine-containing
  • Nadolol — green tea may reduce absorption of this beta-blocker
  • Hepatotoxic drugs — avoid combining with high-dose EGCG

Maximum Dose

Do not exceed: 800 mg EGCG/day; higher doses associated with liver toxicity reports

Full Green Tea Extract (EGCG) Guide

References

  1. (). Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database of Systematic Reviews. DOI
  2. (). Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. American Journal of Clinical Nutrition. DOI