Niacin (Vitamin B3) Overdose: Flushing, Liver Damage & Safe Doses

High-dose niacin can cause uncomfortable flushing and, in severe cases, liver damage. Learn the difference between niacin flush and niacin toxicity, plus safe dosage limits.

Niacin Overdose Risk

High-dose niacin can cause flushing, liver enzyme changes, and other side effects.

Safe Dosage Upper Limits (5 Regional Standards)

StandardRDAUpper Limit (UL)
US (FDA)16 mg35 mg
EU (EFSA)16 mg35 mg
AU (TGA)16 mg35 mg

RDA = Recommended Dietary Allowance. UL = Tolerable Upper Intake Level. Exceeding the UL long-term may cause the toxicity symptoms described above.

Frequently Asked Questions

Is niacin flush dangerous?

Niacin flush (warmth, redness, itching) is generally harmless and temporary. However, sustained-release niacin at high doses can cause liver toxicity without the flush warning. The UL is 35 mg/day for nicotinic acid. Do not use high-dose niacin for cholesterol without medical supervision.

Check if Your Niacin Intake Is Safe

Scan your supplement labels with NutriAudit. Automatically calculate total intake from all sources and detect if you exceed safe limits.

Not medical advice. Always consult a qualified healthcare professional for personal medical decisions.