A vitamin B3 tablet that lowers skin cancer rates
The role of nicotinamide in skin cancer chemoprevention: a review of the literature
Nicotinamide is a form of vitamin B3 available over the counter. In a large Australian trial it reduced new non-melanoma skin cancers by 23% over twelve months in people who had already had two or more. It is inexpensive, well tolerated, and it is not a substitute for sun protection — and in transplant recipients the evidence is conflicted.
Four numbers worth knowing
What we found
The main trial evidence is Australian and reasonably strong.
ONTRAC was a randomised, double-blinded, placebo-controlled phase III trial of 386 participants, split evenly between 500 mg nicotinamide twice daily and placebo for twelve months. Participants were over 18 with at least two histologically confirmed non-melanoma skin cancers in the preceding five years, and were examined by blinded dermatologists every three months for eighteen.
New skin cancers fell by 23%.
The rate of new non-melanoma skin cancers was 23% lower in the nicotinamide group (95% CI 4–38; P=0.02). Basal cell carcinoma was 20% lower and squamous cell carcinoma 30% lower, though neither of those individual figures reached statistical significance.
It works by restoring the energy cells need to repair themselves.
Nicotinamide is the precursor to NAD+, which drives ATP production. Ultraviolet radiation blocks the glycolysis pathway and depletes cellular energy — high-dose UV can cut cellular ATP by 60%, and even suberythemal doses reduce it. That drop does not occur in skin treated with low-dose nicotinamide.
It does not prevent DNA damage — it speeds up the repair.
Nicotinamide does not change the formation of the characteristic UV photolesions. What it does is increase unscheduled DNA synthesis, a marker of DNA excision repair, in ex vivo human skin. Since DNA repair is energy-hungry and UV suppresses cellular energy, restoring that energy is the likely mechanism.
It also blunts the immune suppression that UV causes.
Both UVB and UVA suppress skin immunity, partly by depleting the Langerhans cells that present antigens. In human studies, topical and oral nicotinamide preserved the Mantoux reaction in UV-irradiated volunteers — and notably did not raise the baseline immune response in unirradiated controls, so it corrects a deficit rather than over-stimulating.
In transplant recipients the picture is not settled.
Organ transplant recipients on long-term immunosuppression have far higher skin cancer rates — squamous cell carcinoma up to 65 times that of the general population, often more aggressive and more likely to spread, and basal cell carcinoma up to 16-fold higher. The evidence for nicotinamide as a preventive in this group remains conflicted.
There is no human evidence for melanoma.
Nicotinamide has shown enhanced repair of UV-damaged melanocytes experimentally, but there are currently no human in vivo trials of its chemopreventive properties against melanoma.
The safety profile is the reason it is worth considering at all.
Tolerability is good even at high doses and drug interactions are very few. Gastrointestinal upset is the most common side effect. Rare transient thrombocytopenia, which resolved on stopping, and liver toxicity have been reported in renal and psychiatric patients.
What this means for you
It is not sunscreen in a tablet
A 23% reduction is worth having in someone who keeps growing skin cancers. It is a reduction, not prevention, and it sits alongside sun protection and skin checks rather than replacing either.
Nicotinamide is not niacin
They are different forms of vitamin B3. The flushing people associate with niacin is not a feature of nicotinamide, which is one reason it is tolerable at the doses used here.
The evidence applies to people who already have a history
ONTRAC enrolled people with at least two skin cancers in the previous five years. Nothing here establishes benefit for someone at average risk.
Why this matters
Australia has among the highest rates of skin cancer in the world, and for patients who keep developing them the options beyond surgery and sun protection have been limited. Oral retinoids reduce the rate but carry liver toxicity and lipid problems that make them hard to sustain.
Nicotinamide is interesting precisely because it is unglamorous: cheap, over the counter, and well tolerated. This review was written to set out what the evidence actually supports — a real but modest reduction in a defined group — and, just as importantly, where it does not: melanoma, and transplant recipients.
Why it matters to you
If you have had two or more skin cancers, this is worth raising at your next skin check. It is inexpensive and available without prescription — but it is a conversation to have with your doctor, not a reason to skip sunscreen or surveillance.
What this study cannot tell you
Every study has a boundary, and it is fairer to state it than to leave you to guess.
- This is a narrative review of published work, not new research. It summarises the trials rather than testing them.
- The headline 23% figure comes from a single twelve-month trial in people who already had two or more skin cancers. It does not establish benefit for people at ordinary risk.
- The individual reductions for basal cell and squamous cell carcinoma did not reach statistical significance.
- No human trial has tested nicotinamide against melanoma, so nothing here should be read as protection from it.
- In immunosuppressed patients, including organ transplant recipients, the evidence is explicitly described as conflicted.
Questions people actually ask
Does vitamin B3 prevent skin cancer?
It reduces the rate in a specific group. In an Australian trial of people who had already had at least two non-melanoma skin cancers, 500 mg of nicotinamide twice daily for a year produced 23% fewer new ones than placebo.
That is a meaningful reduction, not prevention, and it has not been shown to help people at average risk or to protect against melanoma.
Is it safe to take?
The safety profile is favourable, with good tolerability even at high doses and very few drug interactions. Gastrointestinal upset is the most common side effect.
Rare cases of transient low platelets, which resolved after stopping, and liver toxicity have been reported in patients with kidney disease and in psychiatric patients. It is worth discussing with your doctor rather than simply starting it.
Is nicotinamide the same as niacin?
Both are forms of vitamin B3, but they are not interchangeable. Nicotinamide is the amide form and does not cause the flushing that niacin is known for.
That difference matters at the doses used for skin cancer prevention, which are considerably higher than a general supplement.
Can I stop wearing sunscreen if I take it?
No. It reduces the rate of new skin cancers by roughly a quarter in people already prone to them — it does not stop ultraviolet damaging the skin.
The mechanism is that it helps cells repair damage that has already happened, which is an argument for preventing that damage in the first place, not against it.
Cite this paper
Sun C, Surjana D, Lim D. The role of nicotinamide in skin cancer chemoprevention: a review of the literature. Opinions and Progress in Cosmetic Dermatology. 2022;2(1):14–19.
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Published 2022 · Summary written and reviewed by Dr Davin Lim, FACD · General information, not personal medical advice.
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