GradedHealth

Does nicotinamide (vitamin B3) help prevent skin cancer? What the trials show

Yes, for people who have had skin cancers: nicotinamide cut new skin cancers by about a quarter in a big trial, but not in organ-transplant recipients.

Published October 2026

Short answer

Yes, in people with earlier skin cancers: 500 mg twice daily cut new non-melanoma skin cancers by 23% in a trial of 386 people, but it did not help organ-transplant recipients, and the benefit faded after stopping. Evidence grade B (Moderate). Phase 3 trial and a meta-analysis of randomised trials; downgraded once for inconsistency between meta-analyses and a null trial in transplant recipients.

Key takeaways

  • In a phase 3 trial of 386 people with at least two earlier skin cancers, 500 mg of nicotinamide twice daily for a year cut new non-melanoma skin cancers by 23% versus placebo [1].
  • Precancerous skin patches (actinic keratoses) were 13% fewer after 12 months, but no benefit was seen once treatment stopped [1].
  • It did not work in 158 organ-transplant recipients: 207 new cancers with nicotinamide versus 210 with placebo [2].
  • Pooled analyses disagree: one found the rate of skin cancers halved (5 trials, 552 people), while another that included transplant recipients found insufficient evidence [3][4].
  • Side effects were mostly digestive, and sunscreen remains the foundation of skin cancer prevention [3][5].

The short version

Yes, nicotinamide (a form of vitamin B3) can help prevent new skin cancers in some people. In a phase 3 trial of 386 people who had already had at least two non-melanoma skin cancers, those taking 500 mg twice daily had 23% fewer new skin cancers over 12 months than those on placebo [1]. It did not work in organ-transplant recipients, and no benefit was seen once treatment stopped [2][1].

What the studies show

People who have had skin cancers. In the ONTRAC trial, new non-melanoma skin cancers were 23% lower with nicotinamide than with placebo (95% CI 4 to 38). Squamous-cell cancers were 30% lower (0 to 51), and basal-cell cancers were 20% lower, a difference that could be due to chance (-6 to 39) [1]. Precancerous rough patches called actinic keratoses were 13% fewer at 12 months [1]. There was no evidence of benefit after nicotinamide was stopped [1].

Pooled results. A 2022 meta-analysis of randomized trials (5 trials, 552 patients) found the rate of skin cancers was halved with nicotinamide (rate ratio 0.50, 95% CI 0.29 to 0.85), though results varied between trials [3]. A 2026 systematic review of trials in people with normal immune systems reported 30% fewer squamous-cell cancers and 13% to 35% fewer actinic keratoses across two trials [5].

Real-world data. In a US veterans' health-record study, 12,287 people who took 500 mg of nicotinamide twice daily were matched with 21,479 who did not. Taking it was linked to 14% lower skin cancer risk, and to 54% lower risk when started after a first skin cancer [6]. This is an observational study, so it cannot prove cause and effect [6].

Creams are a separate question. In a 12-week trial of 50 women with sun-damaged skin, 5% niacinamide cream reduced fine lines, dark spots and red blotchiness on the treated half of the face [7]. We found no trials testing niacinamide creams for skin cancer prevention.

The nuances

Organ-transplant recipients. In a phase 3 trial of 158 transplant recipients with earlier skin cancers, there were 207 new keratinocyte cancers with nicotinamide and 210 with placebo [2]. The trial stopped early because too few people joined [2]. A 2023 meta-analysis that pooled immunocompetent and immunosuppressed patients concluded there was insufficient evidence that nicotinamide reduces keratinocyte cancers (RR 0.82, 95% CI 0.61 to 1.12) [4]. That helps explain why reviews disagree.

Not a lifelong effect. In ONTRAC the protection did not last after people stopped taking nicotinamide [1].

Side effects. Nicotinamide increased digestive side effects in a meta-analysis of randomized trials [3], although ONTRAC found no noteworthy difference in adverse events at 500 mg twice daily [1]. In kidney-transplant recipients, a pilot trial cut the dose from 1,000 mg to 500 mg twice daily because of stomach symptoms [8]. In people on dialysis, flushing, diarrhoea and low platelet counts were reported [9].

Sunscreen still comes first. A 2026 systematic review concluded sunscreen remains the foundation of skin cancer prevention, with nicotinamide showing promise as an addition [5].

What this means for you

The best evidence supports nicotinamide for people with a history of non-melanoma skin cancers and normal immune systems, taken under a doctor's guidance [1][3]. It is not proven for transplant recipients or for people who have never had skin cancer, and it does not replace sunscreen or regular skin checks [2][5]. Talk to a dermatologist before starting. For more, see Nicotinamide (Vitamin B3).

Go deeper

  • Nicotinamide (Vitamin B3) — Taken by mouth, nicotinamide (vitamin B3) at 500 mg twice daily lowered new non-melanoma skin cancers by 23% in a trial of 386 people with earlier skin cancers…

References

  1. A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention.. N Engl J Med, 2015.
  2. Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients.. N Engl J Med, 2023.
  3. Effect of Nicotinamide in Skin Cancer and Actinic Keratoses Chemoprophylaxis, and Adverse Effects Related to Nicotinamide: A Systematic Review and Meta-Analysis.. J Cutan Med Surg, 2022.
  4. The Role of Nicotinamide as Chemo-Preventive Agent in NMSCs: A Systematic Review and Meta-Analysis.. Nutrients, 2023.
  5. Chemoprevention of keratinocyte carcinomas and actinic keratoses in adults who were immunocompetent: a systematic review.. Clin Exp Dermatol, 2026.
  6. Nicotinamide for Skin Cancer Chemoprevention.. JAMA Dermatol, 2025.
  7. Niacinamide: A B vitamin that improves aging facial skin appearance.. Dermatol Surg, 2005.
  8. Oral Nicotinamide for Actinic Keratosis Prevention in Kidney Transplant Recipients: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial.. Transplant Proc, 2023.
  9. Nicotinamide Therapy in Dialysis Patients: A Systematic Review of Randomized Controlled Trials.. Saudi J Kidney Dis Transpl, 2020.