Supplement analysis backed by scientific evidence · PT · ES · DE · FR

← All supplements
Moderate evidenceJoints & skin

Niacinamide

Niacinamide (nicotinamide) is the non-flushing amide form of vitamin B3, and at 500 mg twice daily it cut new skin cancers by about 23% in high-risk immunocompetent patients. That is its one strong indication — it failed in transplant recipients, and it does not do what niacin does for cholesterol.

View on iHerb Ships to 180+ countries · welcome discount for new customers

What the science says

  • Prevents non-melanoma skin cancer in high-risk immunocompetent adults Moderate evidence

    The phase 3 ONTRAC trial randomised 386 people with at least two keratinocyte cancers in the previous five years to 500 mg nicotinamide twice daily or placebo for 12 months. New non-melanoma skin cancers fell by 23% (95% CI 4–38%, p=0.02), with actinic keratoses down 11–20%. The benefit disappeared within six months of stopping, so it is suppression rather than cure — and it rests on one well-conducted trial, not a body of them.

  • Prevents skin cancer in organ transplant recipients Moderate evidence

    ONTRANS tested the identical regimen (500 mg twice daily for 12 months) in 158 solid-organ transplant recipients and was stopped early for futility: new keratinocyte carcinomas were essentially identical between groups. Immunosuppressed patients — the highest-risk group of all — are exactly where this does not work, which is a useful check on how far the ONTRAC result generalises.

  • Topical niacinamide improves acne Limited evidence

    A Cochrane-based review of evidence-based topical acne treatments found 4% niacinamide gel roughly comparable to 1% clindamycin in a handful of small, short trials, with low-certainty evidence throughout. This applies to topical application, not the oral capsules — no good trial shows oral niacinamide clears acne.

  • Is a substitute for niacin for cholesterol Strong evidence

    It is not. Nicotinamide lacks activity at GPR109A, which is why it does not flush — and also why it has none of nicotinic acid's lipid effects. It does not raise HDL or lower LDL or lipoprotein(a). If a product markets a 'flush-free' B3 for cholesterol, the absence of flushing is the signal that it will not work for that purpose.

Dosage & safety

Studied doseSkin-cancer chemoprevention trials used 500 mg twice daily (1 g/day total) for 12 months. The RDA for niacin equivalents is 14–16 mg/day and B-complex products typically supply 20–50 mg. Topical formulations are 2–5%. Doses in the multi-gram range have been used experimentally but carry hepatic risk. Niacinamide is not stored, so the twice-daily split in the trials matters.
SafetyNo flushing, which is its main practical advantage over nicotinic acid. Hepatotoxicity has been reported at gram-level daily doses, particularly above 3 g/day — liver enzymes are worth checking on long-term 1 g/day use. Nausea and headache occur. In dialysis patients given 1–1.5 g/day as a phosphate binder, thrombocytopenia and GI effects were common. Very high doses consume methyl groups and can raise homocysteine. Interacts with carbamazepine (raised levels reported). Anyone taking 1 g/day for skin-cancer prevention should be doing so under dermatology follow-up, not instead of it — and sun protection and lesion surveillance remain the primary intervention. Not banned in sport.

How to take it

TimingTwice daily — niacinamide is not stored, and the 500 mg morning-and-evening split is what the trials used.
With food?With food to reduce nausea.
Worth knowingOn long-term gram-a-day use, have liver enzymes checked; hepatotoxicity is the dose-dependent risk that the absence of flushing hides.

Interactions

With medications

  • carbamazepine

    raised carbamazepine levels have been reported with niacinamide do not take gram-level doses without your prescriber checking drug levels

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does niacinamide prevent skin cancer?

Niacinamide has moderate evidence in one specific group: in the ONTRAC trial, 500 mg twice daily cut new non-melanoma skin cancers by 23% over 12 months in high-risk people with normal immune systems. It did not work in organ transplant recipients, and the benefit disappeared within six months of stopping.

Can niacinamide lower cholesterol like niacin?

No. Niacinamide lacks the receptor activity that makes niacin flush, and that is also why it has none of niacin's effects on HDL, LDL or lipoprotein(a). A 'flush-free' B3 sold for cholesterol will not work for that purpose.

How much niacinamide should I take for skin cancer prevention?

The skin-cancer trials used 500 mg of niacinamide twice daily (1 g/day total) for 12 months; the twice-daily split matters because niacinamide is not stored. Take it under dermatology follow-up, not instead of sun protection and skin checks.

Is niacinamide safe at high doses?

Niacinamide does not cause flushing, but liver toxicity has been reported at gram-level daily doses, particularly above 3 g/day, so have liver enzymes checked on long-term 1 g/day use. It can also raise carbamazepine levels.

Scientific references

Where to buy

NOW Foods, Niacinamide, 500 mg, 100 Veg Capsules

View on iHerb

Ships to 180+ countries · welcome discount for new customers

Referral link — this site may earn a commission on purchases.

Related in Joints & skin