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The tolerable upper intake level (UL), or upper limit, for niacin is 35 mg a day for adults 19 and older. That is the most a day that is unlikely to cause harm for almost everyone; above it, the chance of side effects goes up. It is a ceiling, not a target. The limit counts niacin (nicotinic acid or niacinamide) from supplements and fortified foods, not the niacin naturally in food.
Check your amount
Servings a day
This limit is the same for adults 19 and older, including pregnancy and breastfeeding.
Type the amount from your label to compare it with the upper limit.
Take more than one supplement? Add them all up in the Supplement Checker.
Niacin upper limits by age
| Age | Males | Females | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| Birth to 6 months | Not set | Not set | – | – |
| 7-12 months | Not set | Not set | – | – |
| 1-3 years | 10 mg | 10 mg | – | – |
| 4-8 years | 15 mg | 15 mg | – | – |
| 9-13 years | 20 mg | 20 mg | – | – |
| 14-18 years | 30 mg | 30 mg | 30 mg | 30 mg |
| 19-30 years | 35 mg | 35 mg | 35 mg | 35 mg |
| 31-50 years | 35 mg | 35 mg | 35 mg | 35 mg |
| 51-70 years | 35 mg | 35 mg | – | – |
| 71+ years | 35 mg | 35 mg | – | – |
No upper limit could be set for babies; the National Academies say their intake should come from food and formula only.
How much Niacin you need
| Age | Males | Females | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| Birth to 6 months | 2 mg* | 2 mg* | – | – |
| 7-12 months | 4 mg* | 4 mg* | – | – |
| 1-3 years | 6 mg | 6 mg | – | – |
| 4-8 years | 8 mg | 8 mg | – | – |
| 9-13 years | 12 mg | 12 mg | – | – |
| 14-18 years | 16 mg | 14 mg | 18 mg | 17 mg |
| 19-30 years | 16 mg | 14 mg | 18 mg | 17 mg |
| 31-50 years | 16 mg | 14 mg | 18 mg | 17 mg |
| 51-70 years | 16 mg | 14 mg | – | – |
| 71+ years | 16 mg | 14 mg | – | – |
* Adequate Intake (AI): the amount set when there isn’t enough evidence for an RDA.
What counts toward the Niacin limit
The limit counts niacin (nicotinic acid or niacinamide) from supplements and fortified foods, not the niacin naturally in food.
Labels list niacin in mg (sometimes mg NE). Nicotinic acid and niacinamide both count toward the limit.
What happens with too much Niacin
The National Academies based the niacin UL (35 mg/day for adults) on "flushing as the critical adverse effect". The report describes flushing as the first effect seen with excess intake, usually at lower doses than other effects, and says there is no evidence of harm from niacin that occurs naturally in foods (DRI for Thiamin, Riboflavin, Niacin, Vitamin B6…, 1998, ch. 6).
Sources: Health Canada, Dietary Reference Intakes tables (the joint U.S.-Canada values); National Academies, Dietary Reference Intakes for Sodium and Potassium (2019), DRI summary tables; National Academies, Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998). Limits checked November 8, 2026. More from the NIH: Office of Dietary Supplements Niacin fact sheet.
If you think you or a child took too much of a supplement, call Poison Control at 1-800-222-1222 (U.S., free, 24 hours) or use poison.org. In an emergency, call 911.
General information, not medical advice. Your doctor may recommend a different amount, for example to treat a deficiency. Talk to your doctor or pharmacist before you start, stop or change a supplement, especially if you are pregnant, nursing, take medication or have a medical condition.