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I3C (Indole-3-Carbinol) Side Effects & Safety

Evidence:Moderate
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Generally Safe

Potential Side Effects

  • GI discomfort (nausea, bloating, gas) — more common than with DIM
  • Skin rash in sensitive individuals
  • Dizziness at higher doses
  • Equilibrium-related side effects reported at 800mg+ doses

Drug & Supplement Interactions

  • May reduce efficacy of estrogen-based medications and contraceptives
  • Induces CYP1A2 — may increase metabolism of caffeine, theophylline, and certain drugs
  • May interact with tamoxifen and other hormone therapies

Maximum Dose

Do not exceed: 400mg daily (higher doses increase GI side effects)

Full I3C (Indole-3-Carbinol) Guide

References

  1. RCTBell MC, Crowley-Nowick P, Bradlow HL, Sepkovic DW, Schmidt-Grimminger D, Howell P, Mayeaux EJ, Tucker A, Turbat-Herrera EA, Mathis JM (2000). Placebo-controlled trial of indole-3-carbinol in the treatment of CIN. Gynecologic Oncology. DOI PubMed
  2. RCTReed GA, Arneson DW, Putnam WC, Smith HJ, Gray JC, Sullivan DK, Mayo MS, Crowell JA, Hurwitz A (2005). Single-dose and multiple-dose administration of indole-3-carbinol to women: pharmacokinetics based on 3,3'-diindolylmethane. Cancer Epidemiology, Biomarkers & Prevention. DOI PubMed