Quick answer
Women need 14 mg NE of niacin a day, 18 mg NE during pregnancy and 17 mg NE while breastfeeding. US women average about 21 mg a day from food alone. The upper limit for niacin from supplements is 35 mg a day from age 19, pregnant or not, and 30 mg for teens.1,2
Key facts
- A woman's recommended amount stays at 14 mg NE a day after 50; it does not rise with age.2
- The upper limit for niacin from supplements is the same for women and men: 35 mg a day.2
- In trials of prescription niacin, women reported side effects more often than men.3
- Nicotinamide, often listed as niacinamide, is the form that does not cause flushing.2
What niacin does
Niacin's roles are the same in women and men. The sources describe nothing specific to women, so the graded statements below apply to everyone.2
Niacin contributes to normal energy-yielding metabolism*2,4
Moderate evidence
A well-established nutrient function. Every tissue turns niacin into NAD, a coenzyme that more than 400 enzymes need, many of them in the reactions that move the energy in carbohydrates, fats and proteins into ATP, the cell's energy currency. 'Contributes to normal energy-yielding metabolism' is the wording European regulators permit for the B vitamins, niacin among them. It does not mean extra niacin gives more energy to someone who already gets enough.
Amount studied: Recommended intake: 16 mg NE a day for men and 14 mg NE for women, from food and supplements combined
Niacin is needed for the normal development and function of the body's cells*1,2
Moderate evidence
NIH describes niacin as important for the development and function of the cells in the body. Besides its role in energy, the NAD made from niacin is used by enzymes that control which genes are active and pass signals inside cells, and NADP keeps the cell's antioxidant systems working. The statement is about getting enough niacin, which most people in the US do from food.
Amount studied: Recommended intake: 16 mg NE a day for men and 14 mg NE for women, from food and supplements combined
How much at each stage
| Stage | Recommended amount | Upper limit from supplements |
|---|---|---|
| Girls 9 to 13 | 12 mg NE a day | 20 mg a day |
| Teens 14 to 18 | 14 mg NE a day | 30 mg a day |
| Women 19 to 50 | 14 mg NE a day | 35 mg a day |
| Women 51 and over | 14 mg NE a day | 35 mg a day |
| During pregnancy | 18 mg NE a day | 35 mg a day, or 30 mg for teens |
| While breastfeeding | 17 mg NE a day | 35 mg a day, or 30 mg for teens |
The recommended amounts count food and supplements together. The upper limits count only niacin from supplements and medicines.2
Over 50
Needs do not change after 50, but supplement use climbs: about 40% of women aged 60 and over take a supplement with niacin, and supplements double or triple total intake compared with food alone.2
Multivitamins, B complex products and niacin-only supplements all carry it, so add up the labels and compare the total with the 35 mg limit.1,2
Pregnancy and breastfeeding
The 35 mg upper limit for niacin from supplements also applies in pregnancy and while breastfeeding, and it is 30 mg for anyone under 19. A prenatal vitamin counts toward it.2
Prescription niacin is a different matter. Its label says to stop it when pregnancy is recognized in women taking it for high blood fats (hyperlipidemia), to weigh the risks for those taking it for high triglycerides, and not to breastfeed during treatment.3
Ask your doctor before taking a niacin supplement beyond what your prenatal vitamin provides.
Flushing and side effects
In trials of prescription niacin, the most common side effects were flushing, diarrhea, nausea, vomiting, a worse cough and itching. Up to 88% of people reported flushing, and women reported side effects more often than men.3
For a supplement, the form matters most. Nicotinic acid can cause flushing from about 30 mg, often within half an hour, while nicotinamide does not, and taking nicotinic acid with food makes the flush milder.2
Questions people ask
Do women need more niacin than men?
No. Women need 14 mg NE a day and men 16 mg NE. A woman's needs rise only during pregnancy, to 18 mg NE, and while breastfeeding, to 17 mg NE.1
Can I find a multivitamin without the niacin flush?
Check the form on the label. Nicotinamide, also listed as niacinamide, does not cause flushing, while nicotinic acid can from about 30 mg. Inositol hexanicotinate is sold as flush free, but less of its niacin is absorbed.2
Can I take niacin while breastfeeding?
The 35 mg upper limit for niacin from supplements applies while breastfeeding, as at other times. Prescription niacin is different: its label advises against breastfeeding during treatment. Ask your doctor before taking a niacin supplement while breastfeeding.2,3
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Sources
- National Institutes of Health, Office of Dietary Supplements. Niacin: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-07.
- National Institutes of Health, Office of Dietary Supplements. Niacin: Fact Sheet for Health Professionals. Updated November 18, 2022. Opened 2026-10-07.
- 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.
- European Commission. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods. Official Journal of the European Union, L 136, 25.5.2012, p. 1. Opened 2026-10-01.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.