Nicotinamide (Skin-Cancer Chemoprevention)
Commonly used for
Skin, Hair & Nails
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Wellness uses
Sun-damage protection, clear skin
This is anecdotal, and there isn't strong clinical evidence that it works for everyone.
What is it? / Overview
Nicotinamide is a precursor of NAD+, which restores cellular energy needed for DNA repair after UV exposure and reduces UV-induced immune suppression. A phase 3 randomized trial (ONTRAC) found 500 mg twice daily reduced new non-melanoma skin cancers by 23% over 12 months in immunocompetent adults with a prior history of keratinocyte carcinoma -- one of the strongest RCT evidence bases in this entire database. A separate large trial (ONTRANS) found no benefit in organ-transplant recipients specifically.
How is it used? / Administration
Form: Nicotinamide (niacinamide) oral tablets -- the amide form of vitamin B3; does not cause flushing and does not lower lipids like niacin (nicotinic acid)
Typical dose studied: 500 mg twice daily -- roughly 60x the general-nutrition B3 dose
Timing: Twice daily, continuously -- benefit is lost within months of stopping
This is the same molecule as the niacinamide in general B3 supplements, but at about a 60x higher dose (vs. the general-nutrition RDA level of 14-16 mg/day) for a specific, evidence-backed dermatologic indication (prior keratinocyte carcinoma / heavy sun damage history), not general B3 repletion. Keep clearly separate from niacin/nicotinic acid, which does cause flushing and does affect lipids.
How well does it work? / Evidence
✓ Well-established
Who should avoid it?
Avoid with: End-stage liver disease / Cirrhosis; Organ transplant (on immunosuppression)
Already taking it? Well tolerated even at 1,500 mg/day in trials -- reasonable to continue given this is one of the better-evidenced supplements available, but benefit requires continuous use and is not established in organ-transplant recipients specifically, where a separate large trial was negative.
Research & references
Chen AC et al. (2015). A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention. New England Journal of Medicine. Allen NC et al. (2023). Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients. New England Journal of Medicine. Wehner MR (2025). Keratinocyte Carcinoma. JAMA.
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