Niacin is used in energy metabolism. The two supplement forms behave very differently: nicotinic acid causes flushing at low doses, nicotinamide does not.
Calculator Official intake Study doses Best form Safety Sources
PRI (population reference intake)
Safe upper limit: not set
EFSA safe limit depends on the form: 10 mg for nicotinic acid, 900 mg for nicotinamide. Pick the form below.
EFSA sets niacin per energy eaten (1.6 mg NE per MJ), so there is no single daily number.
RDA (recommended dietary allowance)
| Men | 16 mg |
|---|---|
| Women | 14 mg |
| Pregnancy | 18 mg |
| Breastfeeding | 17 mg |
Safe upper limit: 35 mg a day
Safe limit applies to niacin from supplements and fortified foods (flushing).
Source: National Academies (NASEM) 2019
These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.
2,000 mg a day
HPS2-THRIVE: 25,673 high-risk patients took 2 g extended-release niacin a day (with laropiprant) or placebo for about 4 years. There was no reduction in major vascular events, and more serious infections, bleeding, muscle problems and new diabetes.
Practical pick
Nicotinamide / niacinamide
Why: Nicotinamide (niacinamide) does not cause skin flushing and has fewer side effects than nicotinic acid. EFSA also sets its safe limit much higher (900 mg against 10 mg).
Alternatives: Nicotinic acid causes flushing even at low doses; high doses are a prescription matter.
Meat, fish, peanuts, whole grains, mushrooms.
High-dose nicotinic acid with statins or diabetes medicines needs a doctor.
Nicotinic acid causes flushing; very high doses can harm the liver.
Pregnant, breastfeeding, on medication, or managing a health condition? Check with a doctor or pharmacist before starting a supplement.
Values checked: November 12, 2026.
Independent summaries to read alongside this page. PillMath is not affiliated with these sites.