At what dosage is vitamin B-3 toxic?

Updated: Jun 01, 2020
  • Author: Mark Rosenbloom, MD, MBA; Chief Editor: Michael A Miller, MD  more...
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Vitamin B-3 does not have a toxic dose established for humans. However, adverse effects such as skin flushing can occur at doses of 50 mg/day or greater. While therapeutic doses are considered to typically range from 1,500-6,000 mg/day, these doses carry a risk of liver toxicity, especially if not titrated slowly or in the presence of any preexisting liver disease.

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