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Vitamin B3 (Niacin) 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: Safe with Caution

Potential Side Effects

  • Niacin flush — redness, warmth, and tingling of skin (prostaglandin-mediated); dose-dependent
  • Hepatotoxicity with sustained-release niacin at high doses
  • GI discomfort including nausea, vomiting, and diarrhea at high doses
  • May worsen gout by increasing uric acid levels
  • Niacinamide and NR generally well-tolerated without flushing

Drug & Supplement Interactions

  • Statins — combined use with high-dose niacin may increase myopathy risk
  • Alcohol increases flushing and hepatotoxicity risk with niacin
  • Aspirin (325 mg, taken 30 min before) reduces niacin flush
  • Blood pressure medications — niacin may enhance hypotensive effects
  • Anticoagulants — niacin may enhance effects

Maximum Dose

Do not exceed: 35 mg/day NE from supplements (UL to avoid flushing); therapeutic niacin up to 3,000 mg under medical supervision

Full Vitamin B3 (Niacin) Guide

References

  1. RCTAIM-HIGH Investigators, Boden WE, Probstfield JL, et al. (2011). Niacin in patients with low HDL cholesterol levels receiving intensive statin therapy. New England Journal of Medicine. DOI PubMed
  2. RCTChen AC, Martin AJ, Choy B, et al. (2015). A phase 3 randomized trial of nicotinamide for skin-cancer chemoprevention. New England Journal of Medicine. DOI PubMed
  3. RCTMartens CR, Denman BA, Mazzo MR, et al. (2018). Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nature Communications. DOI PubMed