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Vitamin B2 (Riboflavin) Side Effects & Safety

Evidence:Strong
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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

  • Bright yellow-orange urine (harmless, due to excess riboflavin excretion)
  • Generally very well tolerated even at high doses (400 mg)
  • Rare: mild diarrhea or increased urination at very high doses
  • Possible increased sensitivity to light at very high doses

Drug & Supplement Interactions

  • Tricyclic antidepressants may reduce riboflavin absorption
  • Probenecid decreases gastrointestinal absorption of riboflavin
  • Doxorubicin may interact with riboflavin metabolism
  • Phenobarbital and other barbiturates increase riboflavin metabolism

Maximum Dose

Do not exceed: No established upper limit — low toxicity due to limited absorption at high doses; excess excreted in urine (causing bright yellow color)

Full Vitamin B2 (Riboflavin) Guide

References

  1. RCTSchoenen J, Jacquy J, Lenaerts M (1998). Effectiveness of high-dose riboflavin in migraine prophylaxis: a randomized controlled trial. Neurology. DOI PubMed
  2. ReviewThompson DF, Saluja HS (2017). Prophylaxis of migraine headaches with riboflavin: a systematic review. Journal of Clinical Pharmacy and Therapeutics. DOI PubMed
  3. ReviewPowers HJ (2003). Riboflavin (vitamin B-2) and health. American Journal of Clinical Nutrition. DOI PubMed
  4. RCTKałużna-Czaplińska J, Socha E, Rynkowski J (2011). B vitamin supplementation reduces excretion of urinary dicarboxylic acids in autistic children.. Nutrition research (New York, N.Y.). DOI PubMed