Most of what protects your skin from cancer is familiar: sunscreen, shade, and regular skin checks. So it caught attention when a large 2025 study pointed to something far simpler — an inexpensive, over-the-counter form of vitamin B3 called nicotinamide.
The headlines were enthusiastic, and the underlying science is genuinely encouraging. But the details matter, because nicotinamide helps some people more than others — and it is not a replacement for the basics. Here's what the research shows.
What the 2025 Study Found
Researchers reviewed records from the U.S. Veterans Affairs health system — 33,822 patients with a history of skin cancer — and compared those who took nicotinamide to those who didn't. The study was published in JAMA Dermatology.1
The findings, in plain terms:
- Across everyone studied, nicotinamide was associated with about a 14% reduction in new skin cancers.
- The effect was much larger with timing: patients who started nicotinamide after their first skin cancer saw roughly a 54% reduction in new ones.
- The benefit was seen in non-melanoma skin cancers — basal cell carcinoma and squamous cell carcinoma — the keratinocyte cancers driven by sun damage.
The takeaway the authors emphasized is that starting early matters. The protective signal was strongest when nicotinamide began after a first skin cancer, and it weakened when started later in a long history of multiple cancers.2
This Builds on Earlier Evidence
This isn't a brand-new idea. A landmark randomized trial published in the New England Journal of Medicine in 2015 (the ONTRAC study) found that 500 mg of nicotinamide twice daily reduced new non-melanoma skin cancers by about 23% over a year in high-risk patients.3 On the strength of that trial, many dermatologists have recommended nicotinamide to selected patients for the better part of a decade. The 2025 study adds large, real-world weight to that practice.
How It Works
Nicotinamide supports the skin in two ways that are relevant to cancer prevention. It helps replenish cellular energy (ATP) that DNA-repair machinery needs after ultraviolet damage, and it counteracts the immune suppression that UV light causes in the skin. In other words, it helps the skin repair sun damage and keep its local defenses working.
One important point of confusion: nicotinamide is not the same as niacin. Both are forms of vitamin B3, but niacin causes flushing and can affect cholesterol and blood pressure. Nicotinamide (also labeled niacinamide) does not cause flushing and is the form studied for skin cancer prevention. If you go looking for it, the label matters.
Who Is Most Likely to Benefit
Based on the research, nicotinamide is most relevant for people at elevated risk of non-melanoma skin cancer — particularly those who have already had a basal cell carcinoma, a squamous cell carcinoma, or numerous actinic keratoses. The dose used in the studies was 500 mg twice daily — a standard, inexpensive over-the-counter supplement.
It is not established as a melanoma-prevention strategy, and it is not a reason to ease up on the fundamentals.
What Nicotinamide Is Not
A few honest caveats keep this in perspective:
- It does not replace sun protection or skin checks. The benefit is modest-to-moderate and additive — it works alongside sunscreen, protective clothing, and regular exams, not instead of them.4
- The strongest evidence is for non-melanoma skin cancers, not melanoma.
- "Over-the-counter" does not mean "no conversation." Supplements can interact with medications and conditions (for example, kidney disease can affect dosing). Talk with your dermatologist or physician before starting, and make sure you're buying nicotinamide/niacinamide — not niacin or "no-flush niacin" (inositol hexanicotinate), which are different.
- It's a risk reducer, not a guarantee. Even on nicotinamide, new skin cancers can still develop, which is exactly why ongoing surveillance matters.
The Bottom Line
For the right patient — someone with a history of basal cell or squamous cell carcinoma, or extensive sun damage — nicotinamide is a low-cost, low-risk option with real evidence behind it, and the 2025 data suggest the earlier it's started, the better. It is a useful addition to a prevention plan, not a substitute for one.
If you've had a skin cancer or a lot of actinic keratoses and you're curious whether nicotinamide makes sense for you, it's a good question to raise at your next skin cancer screening.
References
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Breglio KF, Knox KM, Hwang J, et al. Nicotinamide for Skin Cancer Chemoprevention. JAMA Dermatology. 2025. jamanetwork.com ↩
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Vanderbilt University Medical Center. Study reveals efficacy of nicotinamide for skin cancer prevention. 2025. news.vumc.org ↩
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Chen AC, Martin AJ, Choy B, et al. A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention. New England Journal of Medicine. 2015;373(17):1618–1626. nejm.org ↩
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American Academy of Dermatology Association. Skin cancer prevention. aad.org ↩