Condition
    Strong Evidence
    Effectiveness 4/5

    Niacinamide for Skin Cancer

    Nicotinamide reduced new keratinocyte skin cancers by 23% over 12 months in people with a history of at least two prior lesions.

    Overview

    This is one of the better-evidenced supplement findings in dermatology. The ONTRAC phase 3 randomised trial found nicotinamide at 500 mg twice daily reduced new non-melanoma skin cancers by 23 percent over 12 months in high-risk patients.
    Two qualifiers define who this applies to. The population was high-risk: people with at least two non-melanoma skin cancers in the previous five years, not the general public. And the benefit was lost after stopping, meaning this is ongoing suppression rather than a durable change. The result also does not extend to melanoma, which was not the endpoint. Nicotinamide is an adjunct to sun protection and dermatological surveillance in a specific high-risk group, not a general cancer-prevention supplement.

    Verdict

    Likely effective

    A phase 3 RCT in 386 high-risk patients showed a 23% reduction in new non-melanoma skin cancers over 12 months, with benefit lost on discontinuation.

    How It Works

    Ultraviolet radiation damages DNA and simultaneously depletes cellular ATP, which is precisely when the cell most needs energy to run nucleotide excision repair. Nicotinamide is a NAD precursor and restores the energy supply for that repair machinery.
    It also prevents UV-induced immunosuppression, the local shutdown of skin immune surveillance that lets damaged keratinocytes escape clearance. Enhanced repair plus preserved immune surveillance is a coherent explanation for fewer new lesions. Both effects are continuous and dose-dependent, which explains why benefit disappeared once the trial supplement stopped. Nothing about the mechanism produces a lasting change in skin biology.
    Primary mechanism
    NAD replenishment restoring ATP for DNA repair after UV damage
    Secondary mechanism
    Prevention of UV-induced local immunosuppression
    Endpoint reduced
    New basal cell and squamous cell carcinomas
    Not shown for
    Melanoma
    Durability
    None; benefit ends when supplementation stops

    Dosing & Protocol

    The trial dose was nicotinamide 500 mg twice daily, and there is no reason to deviate from it. Note the form: nicotinamide, also labelled niacinamide, not nicotinic acid or extended-release niacin.
    ContextDoseFormTiming
    Trial protocol500 mg twice dailyNicotinamide (niacinamide)Morning and evening
    Total daily1000 mgNicotinamideSplit dosing
    Do not substituteAny doseNicotinic acid or extended-release niacinNot the studied compound
    Assessment window12 monthsNicotinamideContinuous while risk persists
    1. 1

      Confirm you match the trial population· Before starting

      Participants had at least two non-melanoma skin cancers in the preceding five years.

    2. 2

      Discuss it with your dermatologist· Before starting

      This is chemoprevention alongside surveillance, and should be documented in your care.

    3. 3

      Take 500 mg twice daily· Ongoing

      Check the label says nicotinamide or niacinamide, not nicotinic acid.

    4. 4

      Keep sun protection unchanged· Ongoing

      A 23 percent reduction is an addition to sun avoidance, never a replacement for it.

    5. 5

      Maintain skin checks· Per dermatology schedule

      Reduced incidence is not zero incidence; surveillance continues.

    Niacinamide, not niacin

    Nicotinic acid causes flushing and has a different safety profile at gram doses. Only nicotinamide was studied here.

    Evidence

    ONTRAC randomised 386 high-risk patients to nicotinamide 500 mg twice daily or placebo for 12 months. New non-melanoma skin cancers fell by 23 percent, and the benefit was lost after stopping the supplement.

    Phase 3 randomised controlled trial linked to this pairing.

    A phase 3 randomized trial of nicotinamide for skin-cancer chemoprevention

    Score: 9/10
    2015
    rct
    n=386

    Chen AC, Martin AJ, Choy B

    Nicotinamide reduced new non-melanoma skin cancers by 23% over 12 months in high-risk patients.

    View source
    Best available evidence
    Phase 3 RCT, n=386, New England Journal of Medicine
    Effect size
    23% reduction in new non-melanoma skin cancers
    Population
    High-risk patients with prior non-melanoma skin cancers
    Duration
    12 months
    Main limitation
    Benefit not durable after stopping; melanoma not assessed

    Safety

    Nicotinamide at 1 g daily was well tolerated in the trial, with an adverse event profile similar to placebo. It does not cause the flushing associated with nicotinic acid.

    Cautions

    Very high doses have been associated with liver enzyme elevation
    Not the same compound as nicotinic acid
    Caution in significant liver or kidney disease
    Limited data in pregnancy at 1 g daily
    Does not replace sun protection or skin surveillance

    Interactions & Conflicts

    Clinically meaningful drug interactions are limited. The ones listed reflect additive hepatic load or overlapping NAD-pathway supplementation rather than well-documented problems.
    Interacts withSeverityMechanismAction
    Carbamazepine
    moderate
    		Nicotinamide may raise carbamazepine levelsMonitor levels if combining
    Hepatotoxic medicines
    low
    		Additive hepatic load at gram dosesConsider periodic liver function tests
    NR or NMN supplements
    low
    		Same NAD pathway; redundantUse one NAD precursor
    Topical retinoids and sunscreens
    low
    		Complementary skin cancer preventionContinue both as directed

    References

    1. Chen AC et al. A phase 3 randomized trial of nicotinamide for skin-cancer chemoprevention. N Engl J Med. 2015

    Frequently Asked Questions

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