Is niacin safe while breastfeeding?

What does a prescription niacin label say about breastfeeding?

The prescription niacin label has a lactation section, and it is cautious. It says niacin is present in human milk and that the amount increases with a mother's supplementation. It also says there is no information on the effects of the tablets' doses on the breastfed infant or on milk production.¹

The label then draws its conclusion: because of the potential for serious adverse reactions in breastfeeding infants, including liver injury, patients should not breastfeed during treatment. The patient leaflet repeats it in plain words: niacin can pass into breast milk, and a woman and her doctor should decide whether she takes the tablets or breastfeeds, not both.¹

These statements are written for prescription niacin at medicine doses. They do not say what happens at the small amounts in a multivitamin or prenatal vitamin, which the sources checked do not cover.¹

What does NIH say during lactation?

NIH's upper limit for niacin from supplements and medicines is the same during lactation as for other adults and teens, and it is set at the level linked to flushing. Niacin that occurs naturally in food has not been reported to cause harm, and the limit counts only supplements and medicines.^2,3

The limit does not apply to anyone taking niacin under medical supervision. That includes prescription niacin, which is the product the label above is about.²

High doses of nicotinic acid taken for months or years can harm the liver, from raised liver enzymes to hepatitis and liver failure. This is more likely with extended-release forms, and severe cases have followed switching from immediate-release to sustained-release niacin at the same dose.^1,2

What about niacinamide and skin products?

Many questions about niacinamide while breastfeeding are about creams and serums. The sources checked cover niacin taken by mouth, as nicotinic acid or nicotinamide, and do not address skin products. NIH notes that nicotinamide, also called niacinamide, does not cause flushing and has fewer adverse effects than nicotinic acid, which begin at much higher amounts.²

Whether a product applied to the skin matters during breastfeeding is a question for a doctor or pharmacist. The sources here give no answer either way.²

Who should ask a doctor before taking niacin while breastfeeding?

• Anyone prescribed niacin, since the label advises not breastfeeding during treatment.¹
• Anyone who takes a niacin-only supplement, since NIH notes that some contain 500 mg or more a serving, far above the upper limit.²
• Anyone with liver disease, since high doses of nicotinic acid can harm the liver and extended-release forms carry more risk.^1,2
• Anyone who also takes a multivitamin or B complex, to add up the total.²

Questions people ask

Sources

1. Niacin extended-release tablets: prescribing information and patient information (Amneal Pharmaceuticals). DailyMed, U.S. National Library of Medicine. Published September 18, 2026. Opened 2026-10-07.
2. National Institutes of Health, Office of Dietary Supplements. Niacin: Fact Sheet for Health Professionals. Updated November 18, 2022. Opened 2026-10-07.
3. National Institutes of Health, Office of Dietary Supplements. Niacin: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-07.
4. MedlinePlus, U.S. National Library of Medicine. Niacin: drug information (American Society of Health-System Pharmacists). Last revised April 15, 2026. Opened 2026-10-07.
5. National Institutes of Health, Office of Dietary Supplements. Vitamin A and Carotenoids: Fact Sheet for Consumers. Updated March 10, 2025. Opened 2026-10-07.