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Vitamin B1 (Thiamine) 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

  • Very well tolerated at oral doses — no common side effects
  • Rare: allergic reactions with IV thiamine administration
  • Rare: mild GI discomfort at very high doses
  • Warm flushing sensation possible with injectable forms

Drug & Supplement Interactions

  • Loop diuretics (furosemide) increase urinary thiamine excretion — may cause depletion
  • Chronic alcohol use depletes thiamine stores and impairs absorption
  • Antacids may reduce thiamine absorption due to alkaline pH
  • 5-fluorouracil inhibits thiamine phosphorylation

Maximum Dose

Do not exceed: No established upper limit — water-soluble with very low toxicity risk; doses up to 500 mg daily used safely in clinical settings

Full Vitamin B1 (Thiamine) Guide

References

  1. (). Benfotiamine in diabetic polyneuropathy (BENDIP): results of a randomised, double blind, placebo-controlled clinical study. Experimental and Clinical Endocrinology & Diabetes. DOI
  2. (). Thiamine deficiency disorders: diagnosis, prevalence, and a roadmap for global control programs. Annals of the New York Academy of Sciences. DOI
  3. (). Thiamine supplementation in symptomatic chronic heart failure: a randomized, double-blind, placebo-controlled, cross-over pilot study. Clinical Research in Cardiology. DOI