Nicotinamide for Skin Cancer Prevention: What the Research Shows

Nicotinamide, also sold as niacinamide, is one of the forms of vitamin B3. In skin cells exposed to UV light it helps restore cellular energy that DNA repair depends on, and in laboratory and small human studies it reduced the dampening of the skin's immune response that UV causes. That is the biological reason researchers tested it for skin cancer.

It is not the same as niacin (nicotinic acid), the form of B3 that causes flushing and was used for cholesterol. The skin cancer trials used nicotinamide, so the form on the label matters. Our guide to nicotinamide vs niacinamide vs niacin explains the difference in detail.

The best evidence comes from ONTRAC, a randomized, placebo-controlled trial published in The New England Journal of Medicine in 2015 (Chen and colleagues, Australia). It enrolled 386 adults who had had at least two non-melanoma skin cancers (basal cell or squamous cell carcinoma) in the previous five years. Half took nicotinamide 500 mg twice daily for 12 months; half took a placebo.

Over the year, the nicotinamide group had about 23% fewer new non-melanoma skin cancers than the placebo group, and fewer actinic keratoses (rough, sun-damaged precancerous patches). In the six months after people stopped taking it, the difference disappeared. In other words, any effect seemed to last only while the tablets were being taken.

A 23% relative reduction is meaningful for people who develop many skin cancers, but it is not elimination: people in the nicotinamide group still developed new skin cancers and still needed regular skin checks.

Organ transplant recipients: the ONTRANS trial (Allen and colleagues, The New England Journal of Medicine, 2023) gave the same dose to 158 kidney, liver and other transplant recipients with previous skin cancers. After 12 months there was no difference: 207 new keratinocyte cancers in the nicotinamide group and 210 in the placebo group. The trial stopped early because recruitment was slow, so it is smaller than planned, but it did not show a benefit in this heavily immunosuppressed group.

US veterans: a large observational study published in JAMA Dermatology in 2025 looked at more than 33,000 veterans, about 12,000 of whom had taken nicotinamide 500 mg twice daily for at least 30 days. Their risk of a new skin cancer was about 14% lower overall, and the association was strongest, about 54% lower, when nicotinamide was started after a first skin cancer rather than after several. The effect was clearest for squamous cell carcinoma. Because this was not a randomized trial, it shows an association, not proof that nicotinamide caused the difference.

Melanoma: none of these studies showed that nicotinamide prevents melanoma, and it should not be taken with that expectation.

ONTRAC, ONTRANS and the veterans study all used 500 mg of nicotinamide twice a day, a total of 1,000 mg daily. That is far more vitamin B3 than a multivitamin contains, which is why it is better thought of as a medical dose than as a vitamin top-up.

More is not better. At much higher doses (several grams a day), nicotinamide has been linked to liver problems, and there is no evidence that going above the studied dose adds protection. Splitting the dose into two was how the trials did it, and the benefit appeared only while people kept taking it.

The trial evidence is for a narrow group: adults, mostly fair-skinned and middle-aged or older, who had already had two or more non-melanoma skin cancers. ONTRAC was run in Australia, where skin cancer rates are among the highest in the world.

It has not been tested as everyday prevention in young, healthy people who have never had skin cancer, so there is no evidence it lowers risk for them. Some dermatologists now discuss nicotinamide with patients who keep developing keratinocyte cancers or have many actinic keratoses, as an add-on to sun protection and regular skin checks, not instead of them.

Talk to your doctor or dermatologist before starting nicotinamide, and especially if any of these apply:

You have had skin cancer, or are being followed for it: your dermatologist can tell you whether your history matches the people who were studied. You have had an organ transplant or take immunosuppressants: the ONTRANS trial did not show a benefit, and your transplant team should be involved in any supplement decision. You have kidney disease or are on dialysis: the body clears nicotinamide through the kidneys, and a drop in platelets has been reported in dialysis patients. You have liver disease. You are pregnant or breastfeeding: high doses have not been studied. You take other medicines, including some seizure medicines (carbamazepine, primidone), or already take vitamin B3 in another product.

Tell your dermatologist if you start it, so it is on your record.

Nicotinamide does not block UV light, does not stop sunburn, and was tested alongside, not instead of, sun protection. Broad-spectrum SPF 30+ sunscreen, shade, clothing and hats remain the first line, and anyone with a history of skin cancer still needs regular full-skin checks.

If you are reading this because you have a lot of sun damage or a spot that worries you, the more useful first step is to look at that spot: a new, changing, bleeding or non-healing spot should be seen by a doctor whatever supplement you take.