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DIM (Diindolylmethane) 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

  • Darkened urine — a harmless discoloration due to DIM metabolites; often startling but not dangerous
  • GI symptoms — nausea, gas, or changes in bowel movements
  • Headache (uncommon)
  • Menstrual changes — cycle length or flow may shift as estrogen metabolism adjusts; usually normalizes

Drug & Supplement Interactions

  • Estrogen-sensitive medications (tamoxifen, aromatase inhibitors) — DIM modulates estrogen metabolism; consult oncologist before combining
  • Hormonal contraceptives — potential interaction with estrogen metabolism; efficacy impact unknown
  • CYP1A2 substrates — DIM may induce CYP1A2 enzyme activity; may affect caffeine, theophylline metabolism
  • Thyroid medications — some reports of DIM affecting thyroid hormone levels; monitor thyroid function

Maximum Dose

Do not exceed: 200mg enhanced-absorption DIM daily; higher doses may cause GI disturbance and are not well-studied

Full DIM (Diindolylmethane) Guide

References

  1. (). Pilot study: effect of 3,3'-diindolylmethane supplements on urinary hormone metabolites in postmenopausal women with a history of early-stage breast cancer. Nutrition and Cancer. DOI
  2. (). A randomized, placebo-controlled trial of diindolylmethane for breast cancer biomarker modulation in patients taking tamoxifen. Breast Cancer Research and Treatment. DOI