Nicotinamide, also called niacinamide, is the amide form of vitamin B3 and a dietary, supplemental, and topical ingredient studied in nutrition, NAD-related metabolism, dermatology, kidney phosphate control, eye health, and safety contexts (NIH ODS).
Nicotinamide is one of the major forms included under the broader term niacin, and the body uses absorbed niacin forms to support NAD and NADP, vitamin-derived coenzymes involved in cellular energy metabolism and redox reactions (NIH ODS). Human evidence is strongest for correcting or preventing niacin deficiency as part of vitamin B3 nutrition, oral nicotinamide for selected high-risk skin-cancer prevention research, and topical niacinamide for several dermatology outcomes such as acne, hyperpigmentation, melasma, visible aging signs, and barrier support (Research) (Research) (Research). Evidence is more mixed or population-dependent for transplant-recipient keratinocyte-cancer prevention, type 1 diabetes prevention, chronic-kidney-disease phosphate control, and glaucoma-related outcomes (Research) (Research).
Ingredient Identity
- Official name(s): Nicotinamide; niacinamide; pyridine-3-carboxamide.
- Vitamin family: Vitamin B3 / niacin family.
- Related forms: Nicotinic acid, nicotinamide riboside, nicotinamide mononucleotide, NAD, and NADP are related but distinct niacin-family compounds (NIH ODS).
- Classification: Water-soluble B vitamin form and NAD/NADP precursor (NIH ODS).
- CAS number: 98-92-0.
- Endogenous vs exogenous: Nicotinamide is obtained from diet or supplements and is also generated during niacin and NAD metabolism in the body (NIH ODS).
- Topical identity: Niacinamide is used in topical gels, creams, serums, moisturizers, and emollients in dermatology and cosmetic research (Review).
Ingredient Snapshot
- Classification: Nicotinamide is a non-flushing form of vitamin B3 and a precursor for NAD-related metabolism (NIH ODS).
- Endogenous vs exogenous status: The body can obtain niacin from foods, fortified foods, supplements, and tryptophan conversion, while nicotinamide also appears in NAD turnover pathways (NIH ODS).
- Primary human research domains: Major human research areas include Nutrition and Deficiencies, Beauty and Skin Health, Cancer Research, Kidney Health, Eye Health, Diabetes and Glycemic Control, and Autoimmune Disorders (Research) (Research) (Research).
- Common study formats: Human studies include randomized controlled trials, phase 2 and phase 3 trials, pharmacokinetic studies, dermatology split-face or vehicle-controlled trials, and systematic reviews (Research) (Research) (Review).
- Pharmacokinetic characterization status: Human oral pharmacokinetic studies report rapid peak concentrations in many high-dose settings and half-life values that vary by dose, formulation, and population (Research) (Research).
- Topical characterization status: Topical studies commonly use 2–5% niacinamide/nicotinamide, with study durations often ranging from 4 to 12 weeks depending on the skin outcome (Research) (Research).
- Regulatory context (U.S./EU): NIH ODS describes niacin as a vitamin with established dietary reference intakes, and FDA lists niacinamide/nicotinamide in a food-substance context as a nutrient supplement ingredient (NIH ODS) (FDA).
- Evidence maturity: Evidence is Strong for vitamin B3 nutritional identity, Moderate for selected oral and topical dermatology outcomes, and Mixed for several disease-specific pharmacologic uses outside nutrition and dermatology (NIH ODS) (Review).
Introduction
Nicotinamide is the amide form of niacin, also known as vitamin B3, and is one of the major forms included under the niacin family alongside nicotinic acid and related derivatives (NIH ODS). Niacin is naturally present in many foods, added to fortified foods, and available in supplements, while nicotinamide is also generated when NAD-related compounds are metabolized (NIH ODS).
People look up nicotinamide for both oral and topical reasons. Oral research includes vitamin B3 nutrition, non-melanoma skin-cancer prevention in high-risk groups, kidney phosphate studies, type 1 diabetes prevention trials, and eye-health research, while topical research includes acne, pigmentation, melasma, visible aging signs, and barrier-related outcomes (Research) (Research) (Research).
This article is informational only, describes nicotinamide as a biochemical substance studied in human research, and does not provide medical or dosing advice.
Quick Summary
- Nicotinamide, also called niacinamide, is a form of vitamin B3 that supports NAD and NADP metabolism and is distinct from nicotinic acid, the flushing form of niacin (NIH ODS).
- Oral nicotinamide has a strong nutritional evidence base as part of niacin biology and a meaningful dermatology evidence base in high-risk non-melanoma skin-cancer prevention research (NIH ODS) (Research).
- Topical niacinamide has human evidence for acne, hyperpigmentation, melasma, visible aging signs, seborrheic dermatitis, and barrier-related outcomes, with many studies using 4–5% preparations over 4–12 weeks (Research) (Research).
- Human oral pharmacokinetic studies report peak plasma concentrations often around 30 minutes at doses up to 6 g, while reported half-life values vary from short dose-dependent values to approximately 7–9 hours or a median 9.3 hours in specific high-dose settings (Research) (Research) (Research).
- Evidence is mixed for transplant-recipient keratinocyte-cancer prevention, type 1 diabetes prevention, and chronic-kidney-disease phosphate control because large trials did not consistently show benefit in those populations (Research) (Research) (Research).
- Oral high-dose nicotinamide is not the same as topical niacinamide, and oral safety findings should not be automatically applied to cosmetic skin products (NIH ODS) (Review).
- Topical tolerability is generally favorable in cosmetic safety assessments, but irritation, stinging, or sensitivity can still occur in individual users depending on formula, concentration, skin barrier condition, and other ingredients (Review).
Human Research Findings by Condition
Nutrition and Deficiencies
Nicotinamide is part of the established human nutrition evidence base for niacin, and niacin deficiency is a recognized nutritional condition. NIH ODS describes niacin as vitamin B3, identifies nicotinamide as one of its major forms, and lists dietary reference intakes for niacin equivalents (NIH ODS).
Key human study
Dose studied: Dietary reference intake context; adult RDAs are 16 mg NE/day for men and 14 mg NE/day for women.
Population: General population.
Duration: Ongoing dietary requirement context.
NIH ODS describes niacin as a water-soluble B vitamin required for NAD and NADP metabolism and provides age- and sex-specific dietary reference intakes in niacin equivalents (NIH ODS). The source also explains that foods, fortified foods, supplements, and tryptophan conversion can contribute to niacin status (NIH ODS).
Result: Human studies observed short-term physiological effects
Evidence strength: Strong
Study source: (NIH ODS)
Additional human study
Dose studied: Population intake and safety reference context.
Population: European general population.
Duration: Dietary reference-value context.
EFSA dietary reference work uses niacin equivalents for intake assessment and distinguishes niacin forms in reference-value and safety discussions (EFSA). This supports classifying nicotinamide as a well-established nutrient form rather than a purely experimental compound (EFSA).
Result: Human studies observed short-term physiological effects
Evidence strength: Strong
Study source: (EFSA)
Beauty and Skin Health
Beauty and Skin Health is one of the strongest human-research areas for topical niacinamide. Trials have studied acne, hyperpigmentation, melasma, aging-skin appearance, atopic-dermatitis barrier support, and seborrheic dermatitis using topical gels, creams, moisturizers, or emollients (Research) (Research) (Review).
Key human study
Dose studied: 4% nicotinamide gel.
Population: 76 patients with inflammatory acne vulgaris.
Duration: 8 weeks.
A randomized trial compared topical 4% nicotinamide gel with 1% clindamycin gel in inflammatory acne and reported comparable efficacy between the two topical treatments (Research). This supports topical nicotinamide as an acne-relevant ingredient in human research, although acne evidence varies by study design, comparator, and skin type (Research).
Result: Randomized human trial reported a statistically significant improvement
Evidence strength: Moderate
Study source: (Research)
Additional human study
Dose studied: 5% niacinamide topical facial product.
Population: Women with visible aging signs.
Duration: 12 weeks.
A topical facial-skin study reported that 5% niacinamide improved several visible aging-related outcomes, including yellowing, wrinkling, red blotchiness, and hyperpigmented spots over 12 weeks (Research). This study supports a structured topical section for aging-skin appearance rather than treating niacinamide only as an oral nutrient (Research).
Result: Human clinical study reported a modest improvement
Evidence strength: Moderate
Study source: (Research)
Cancer Research
Oral nicotinamide has been studied in Cancer Research mainly for non-melanoma skin-cancer and actinic-keratosis prevention in high-risk populations. Evidence is strongest in immunocompetent high-risk adults and weaker or negative in organ-transplant recipients, so population context is important (Research) (Research).
Key human study
Dose studied: 500 mg twice daily oral nicotinamide.
Population: 386 high-risk adults with previous non-melanoma skin cancers.
Duration: 12 months.
The ONTRAC phase 3 randomized trial found that oral nicotinamide reduced new non-melanoma skin cancers and actinic keratoses during active treatment in high-risk immunocompetent adults (Research). The effect was observed during the treatment period and should be interpreted in that high-risk population rather than generalized to all users (Research).
Result: Randomized human trial reported a statistically significant improvement
Evidence strength: Moderate
Study source: (Research)
Additional human study
Dose studied: 500 mg twice daily oral nicotinamide.
Population: Organ-transplant recipients.
Duration: 12 months.
A phase 3 trial in organ-transplant recipients did not show a significant reduction in keratinocyte cancers or actinic keratoses with nicotinamide compared with placebo (Research). This finding shows that oral nicotinamide’s skin-cancer research signal is population-dependent and not uniformly positive across immunosuppressed groups (Research).
Result: Human clinical study reported no clear effect
Evidence strength: Mixed
Study source: (Research)
Kidney Health
Kidney Health research has studied nicotinamide as a phosphate-lowering intervention, especially in hemodialysis or chronic-kidney-disease populations. Results are mixed because some dialysis studies reported phosphorus reduction, while a stage 3b/4 CKD trial did not significantly lower phosphate or FGF23 over 12 months (Research) (Research).
Key human study
Dose studied: Oral nicotinamide in a CKD phosphate-control trial.
Population: Stage 3b/4 chronic kidney disease.
Duration: 12 months.
A randomized trial in stage 3b/4 CKD found that nicotinamide, with or without lanthanum carbonate, did not significantly lower serum phosphate or FGF23 over 12 months (Research). This finding limits confidence for non-dialysis CKD phosphate control (Research).
Result: Human clinical study reported no clear effect
Evidence strength: Mixed
Study source: (Research)
Additional human study
Dose studied: Oral nicotinamide in hemodialysis phosphate-control trials.
Population: Hemodialysis patients.
Duration: 8 weeks in one double-blind trial.
A double-blind hemodialysis trial reported lower serum phosphorus and increased HDL cholesterol with nicotinamide, but thrombocytopenia was reported as a safety concern (Research). This suggests a phosphate-related signal in dialysis populations while also requiring careful safety interpretation (Research).
Result: Randomized human trial reported a statistically significant improvement
Evidence strength: Mixed
Study source: (Research)
Diabetes and Glycemic Control
Diabetes and Glycemic Control research includes large type 1 diabetes prevention trials using high-dose nicotinamide in at-risk individuals. The major prevention trial did not establish a protective effect, so the evidence should be described as negative or inconclusive rather than supportive (Research).
Key human study
Dose studied: High-dose oral nicotinamide in a prevention trial.
Population: First-degree relatives of people with type 1 diabetes who had islet-cell antibodies.
Duration: Up to 5 years.
The European Nicotinamide Diabetes Intervention Trial tested whether nicotinamide could prevent or delay type 1 diabetes in antibody-positive first-degree relatives and did not establish a prevention benefit (Research). This makes type 1 diabetes prevention an area where mechanistic interest did not translate into clear clinical benefit in a large trial (Research).
Result: Human clinical study reported no clear effect
Evidence strength: Moderate
Study source: (Research)
Eye Health
Eye Health research has examined nicotinamide in glaucoma-related retinal function and neuroenhancement contexts. The evidence is early because trials are relatively small and sometimes use combination designs that limit attribution to nicotinamide alone (Research) (Research).
Key human study
Dose studied: Oral nicotinamide supplementation in a crossover trial.
Population: People with glaucoma.
Duration: Short-term crossover study.
A randomized crossover trial reported improved inner retinal function with nicotinamide supplementation in glaucoma patients (Research). The study supports a physiological signal but does not establish long-term disease-modifying benefit (Research).
Result: Randomized human trial reported a statistically significant improvement
Evidence strength: Emerging
Study source: (Research)
Additional human study
Dose studied: Nicotinamide plus pyruvate.
Population: Open-angle glaucoma patients.
Duration: Phase 2 short-term trial.
A phase 2 trial studied nicotinamide plus pyruvate for retinal ganglion-cell function in open-angle glaucoma, but the combination design makes it difficult to attribute outcomes to nicotinamide alone (Research). This supports continued research while keeping claims cautious (Research).
Result: Human clinical studies reported mixed findings
Evidence strength: Emerging
Study source: (Research)
Autoimmune Disorders
Autoimmune Disorders evidence includes older human research using nicotinamide in combination therapy for bullous pemphigoid. Because the study combined nicotinamide with tetracycline, the result cannot be attributed to nicotinamide alone (Research).
Key human study
Dose studied: Nicotinamide plus tetracycline combination therapy.
Population: Bullous pemphigoid patients.
Duration: 8 weeks.
An open-label randomized trial compared tetracycline plus nicotinamide with prednisone in bullous pemphigoid patients (Research). The combination design and disease-specific context mean this evidence does not establish nicotinamide alone as a general autoimmune intervention (Research).
Result: Human clinical studies reported mixed findings
Evidence strength: Limited
Study source: (Research)
Dosage & Study Snapshot (Research Context)
Human nicotinamide research includes dietary niacin-equivalent exposure, oral supplement-level dosing, high-dose pharmacokinetic studies, medical-condition trials, and topical dermatology concentrations. The lowest exposures are dietary niacin-equivalent intakes, while topical studies usually describe percent concentration rather than systemic dose. These are research contexts, not personal dosing instructions.
14–16 mg NE/day dietary reference intake context:
Adult niacin RDAs are listed as 16 mg NE/day for men and 14 mg NE/day for women, with higher values in pregnancy and lactation (NIH ODS). This exposure band reflects nutritional requirement context rather than dermatology or pharmacologic trial dosing. Niacin equivalents include preformed niacin and tryptophan-derived niacin contribution. This is the baseline nutrition framework for nicotinamide as a vitamin B3 form.
Result: Nutritional adequacy context
Evidence strength: Strong
Notes / limitations: Dietary reference intakes do not define topical skincare concentration or pharmacologic trial dosing.
2–5 mg per serving in many plant foods and 5–10 mg per serving in many animal foods:
NIH ODS reports that many animal-based foods provide about 5–10 mg niacin per serving, while many plant foods provide about 2–5 mg per serving (NIH ODS). This exposure band helps distinguish ordinary dietary niacin exposure from high-dose oral nicotinamide trials. Food niacin may occur as nicotinic acid, nicotinamide, NAD, NADP, or bound forms depending on the food. Bioavailability can differ by source and processing.
Result: Nutritional exposure
Evidence strength: Strong
Notes / limitations: Food niacin exposure is not equivalent to topical niacinamide application.
500 mg or more per serving supplement-market context:
NIH ODS states that some niacin-only supplements contain 500 mg or more per serving, which is much higher than the adult RDA (NIH ODS). Nicotinamide does not cause the flushing typical of nicotinic acid because it has a different chemical structure (NIH ODS). This exposure range overlaps with oral dermatology trials but should not be generalized across all populations. Safety context matters more as oral intakes move far above nutritional requirements.
Result: Research-relevant exposure
Evidence strength: Strong
Notes / limitations: Supplement label amounts do not establish an appropriate dose for an individual.
500 mg twice daily oral nicotinamide in skin-cancer prevention trials:
The ONTRAC phase 3 trial used 500 mg twice daily oral nicotinamide for 12 months in high-risk immunocompetent adults and reported fewer new non-melanoma skin cancers and actinic keratoses during treatment (Research). A transplant-recipient trial using the same general oral dose did not reduce keratinocyte cancers or actinic keratoses over 12 months (Research). This dose band is therefore evidence-supported in a specific research context but population-dependent. It should not be treated as a universal skin-cancer prevention recommendation.
Result: Mixed findings
Evidence strength: Moderate
Notes / limitations: Immunocompetent high-risk adults and transplant recipients had different trial outcomes.
750 mg twice daily oral nicotinamide in stage 3b/4 CKD research:
A CKD trial studied oral nicotinamide with or without lanthanum carbonate and did not significantly lower serum phosphate or FGF23 over 12 months (Research). This dose band belongs to a medical research context rather than ordinary supplement or skincare use. Kidney-disease populations also require separate safety interpretation. The trial’s neutral result limits confidence for non-dialysis CKD phosphate control.
Result: No clear effect
Evidence strength: Moderate
Notes / limitations: CKD phosphate findings should not be extrapolated to general wellness or skincare.
500–1500 mg/day oral nicotinamide in hemodialysis phosphate studies:
NIH ODS summarizes several small hemodialysis studies using 500–1500 mg/day nicotinamide and notes diarrhea and thrombocytopenia as common adverse effects in that context (NIH ODS). Hemodialysis trials reported phosphorus-lowering signals, but tolerability and platelet effects remain important limitations (Research) (Research). This exposure band is medically specific and should not be applied to healthy users. The population, monitoring context, and adverse-event profile matter.
Result: Mixed findings
Evidence strength: Moderate
Notes / limitations: Dialysis findings require clinical monitoring and do not translate into general supplement guidance.
1–6 g single-dose oral pharmacokinetic studies:
A human pharmacokinetic study using 1–6 g oral nicotinamide found dose-dependent plasma concentrations and clearance, with half-life approximately 7–9 hours for the two highest doses (Research). Another high-dose PK study reported that maximum plasma levels were observed by about 30 minutes in most patients taking up to 6 g (Research). These data are useful for Tmax and half-life structure but involve high research doses. They should not be used to infer timing for low-dose nutrition or topical use.
Result: Human studies observed short-term physiological effects
Evidence strength: Moderate
Notes / limitations: High-dose PK values do not define cosmetic topical timing.
10 g oral pharmacokinetic comparison:
A high-dose patient PK study reported delayed absorption in most patients taking 10 g oral nicotinamide compared with lower doses up to 6 g (Research). This supports dose-dependent and formulation-dependent absorption rather than a single universal Tmax. High gram-level doses are pharmacologic research exposures. Adverse effects and tolerability become more important at these levels.
Result: Human studies observed short-term physiological effects
Evidence strength: Moderate
Notes / limitations: This is not a consumer skincare or routine nutrition exposure band.
4% topical nicotinamide / niacinamide for acne and melasma:
Topical 4% nicotinamide gel was compared with 1% clindamycin gel in inflammatory acne over 8 weeks and showed comparable efficacy (Research). Topical 4% niacinamide also showed clinical and objective improvement in melasma compared with 4% hydroquinone in an 8-week randomized trial, although hydroquinone performed better on some lightening outcomes (Research). This concentration is one of the best-supported topical research ranges. It is studied as a skin-application concentration, not a systemic dose.
Result: Statistically significant improvement
Evidence strength: Moderate
Notes / limitations: Topical concentration does not translate into oral dose.
5% topical niacinamide for acne and aging-skin appearance:
A topical acne trial reported that 5% nicotinamide gel was similarly effective to 2% clindamycin gel in mild to moderate acne over 8 weeks (Research). A separate facial-aging study reported that 5% niacinamide improved visible aging-related outcomes over 12 weeks (Research). This dose band is highly relevant to skincare users because many cosmetic formulas use percent concentrations. The evidence supports research-context discussion, not a guarantee that every 5% product will perform the same.
Result: Modest improvement
Evidence strength: Moderate
Notes / limitations: Vehicle, formula quality, barrier condition, and other ingredients can affect tolerability and visible results.
Key Takeaways from Human Research
- Nicotinamide is an established vitamin B3 form with clear relevance to NAD and NADP metabolism (NIH ODS).
- Oral 500 mg twice daily nicotinamide reduced new non-melanoma skin cancers in high-risk immunocompetent adults, but the same broad approach did not show benefit in a transplant-recipient trial (Research) (Research).
- Topical 4–5% niacinamide/nicotinamide has repeated human-study support across acne, melasma, pigmentation, and aging-skin appearance outcomes (Research) (Research) (Research).
- Oral PK studies provide usable numbers for AI extraction: peak plasma levels often occurred around 30 minutes up to 6 g, and reported half-life values ranged by study and population (Research) (Research).
- Kidney phosphate evidence is mixed, with some hemodialysis studies showing phosphorus reduction and a stage 3b/4 CKD trial showing no significant phosphate or FGF23 reduction (Research) (Research).
- Topical tolerability is generally favorable in cosmetic safety assessment, but individual reactions can occur and depend on formula, skin barrier, and co-ingredients (Review).
Origin & Natural Occurrence
Niacin occurs naturally in many foods, including poultry, beef, fish, nuts, legumes, and grains, and it is also added to some fortified foods (NIH ODS). NIH ODS reports that many animal foods provide about 5–10 mg niacin per serving, while many plant foods provide about 2–5 mg per serving (NIH ODS).
Nicotinamide is one form of niacin and can also arise from metabolism of NAD-related compounds in the body (NIH ODS). Tryptophan can contribute to niacin status because the body can convert some tryptophan into NAD, and the common conversion estimate is 60 mg tryptophan to 1 mg niacin equivalent (NIH ODS).
Topical niacinamide used in skincare products is manufactured as an ingredient rather than consumed as a food exposure. Its topical use should be evaluated by skin concentration, vehicle, and dermatology evidence rather than by dietary niacin-equivalent intake (Review).
How It Behaves in the Body
Nicotinamide supports cellular metabolism because absorbed niacin forms are converted into NAD, and NAD can also be converted into NADP in most tissues (NIH ODS). NAD and NADP help enzymes move electrons in redox reactions, which is a basic chemical process cells use to convert food energy, maintain antioxidant systems, and support cellular repair functions (NIH ODS).
In oral pharmacokinetic studies, nicotinamide enters the bloodstream quickly in many high-dose settings. One patient PK study reported maximum plasma levels by about 30 minutes in most patients ingesting up to 6 g, while 10 g showed delayed absorption in most patients (Research).
Half-life varies by study design, dose, and population. One healthy-volunteer PK study reported half-life values of approximately 7–9 hours at the two highest oral doses studied, while a cancer-patient PK study reported a median half-life of 9.3 hours with a range of 4.2–26.8 hours (Research) (Research).
On the skin, topical niacinamide is studied for local effects rather than systemic vitamin repletion. Clinical and mechanistic dermatology literature describes effects related to pigmentation appearance, barrier function, inflammation, sebum-related outcomes, and visible aging measures, but exact mechanisms can vary by concentration, vehicle, and endpoint (Research) (Review).
Absorption & Delivery Formats
Oral immediate-release
Oral nicotinamide is well represented in human PK, nutrition, skin-cancer prevention, kidney phosphate, diabetes-prevention, and eye-health research (Research) (Research). High-dose oral PK studies report rapid plasma peaks in many participants, including peak levels around 30 minutes up to 6 g in one patient study (Research).
Oral extended-release
Nicotinamide formulation can affect absorption and tolerability. A formulation PK study examined absorption characteristics and adverse-effect incidence with different nicotinamide formulations, supporting the idea that oral timing is not determined by dose alone (Research).
Sublingual
No major sublingual nicotinamide evidence base was identified among the main human sources used for this article. Claims about sublingual onset, Tmax, or superiority should not be inferred from oral tablet or topical studies.
Transdermal
Topical niacinamide has meaningful skin evidence, but topical skincare use should not be described as systemic transdermal vitamin B3 replacement unless direct systemic absorption data are available. Most topical studies evaluate local skin endpoints such as acne lesions, pigmentation, melasma severity, barrier measures, or visible aging signs (Research) (Research).
Injectable / IV (research or clinical only)
Injectable nicotinamide is not a major route in the ingredient evidence summarized here. The main human pharmacokinetic and clinical evidence base for nicotinamide is oral and topical.
Topical gels, creams, moisturizers, serums, and emollients
Topical niacinamide is studied in several vehicle types, including gels for acne, creams for melasma or seborrheic dermatitis, facial products for visible aging, and emollients for barrier-related outcomes (Research) (Research) (Research). The best-supported research concentrations for common skincare questions are often 4–5%, while cosmetic safety assessments include tolerability information at several concentrations (Review).
Quick Facts at a Glance
Onset (reported)
For oral pharmacokinetics, plasma exposure can begin quickly, and one high-dose patient study reported maximum plasma levels by about 30 minutes in most patients taking up to 6 g nicotinamide (Research). For topical skincare, “onset” is usually measured as visible or clinical change over weeks rather than minutes or hours (Research).
Time to peak (Tmax)
Human oral Tmax is study-dependent, but one PK study reported peak plasma levels by about 30 minutes in most patients up to 6 g, with delayed absorption in most patients at 10 g (Research). Tmax for topical cosmetic outcomes is not usually measured as a plasma peak because topical studies focus on skin endpoints.
Half-life (t½)
Reported oral half-life values vary across human studies. A healthy-volunteer PK study reported approximately 7–9 hours at higher doses, while a cancer-patient PK study reported a median half-life of 9.3 hours with a range of 4.2–26.8 hours (Research) (Research).
Typical duration
Oral plasma exposure can extend for several hours in PK studies, but clinical-outcome duration differs by research area. Topical dermatology trials commonly evaluate outcomes after 4 weeks for pigmentation/lightness, 8 weeks for acne or melasma, and 12 weeks for visible aging or seborrheic dermatitis contexts (Research) (Research) (Research).
Absorption routes studied
Oral and topical routes are the best represented in the human evidence base. Oral studies measure plasma concentrations or systemic outcomes, while topical studies measure local skin outcomes such as acne lesions, pigmentation, barrier function, or aging-related appearance (Research) (Research).
Formulation differences
Oral formulation can affect absorption and tolerability, especially in high-dose pharmacokinetic settings (Research). Topical outcomes also depend on vehicle type because gels, creams, moisturizers, serums, and emollients differ in skin feel, penetration behavior, and irritation potential (Review).
Variability drivers
Dose, formulation, population, kidney function, disease state, and measurement timing can influence oral nicotinamide findings (Research). For topical products, variability can depend on concentration, vehicle, skin barrier condition, oiliness, co-ingredients, and adherence across weeks of use (Research).
Tolerance / adaptation
Topical tolerability is generally favorable in cosmetic safety assessment, with reported no stinging up to 10% and no irritation in use tests up to 5% in the reviewed data (Review). Oral tolerability is more dose- and population-dependent, with digestive adverse events and thrombocytopenia concerns reported in some high-dose or kidney-disease contexts (NIH ODS).
Evidence strength snapshot
The evidence is Strong for nicotinamide’s vitamin B3 identity and NAD-related nutritional role, Moderate for several oral and topical dermatology contexts, and Mixed for kidney phosphate, transplant-recipient skin-cancer prevention, diabetes prevention, and glaucoma-related research (NIH ODS) (Review) (Research).
Other Physiological Contexts Studied (If Applicable)
- Seborrheic dermatitis: An open randomized study in 48 patients reported improvement with 4% nicotinamide cream versus vehicle over 12 weeks, but open-label design limits confidence (Research).
- Atopic dermatitis barrier support: A randomized study reported that niacinamide-containing body emollients improved symptoms, quality of life, and skin-barrier measures in mild atopic dermatitis over 4 weeks (Research).
- Skin-barrier penetration context: Human skin-barrier and topical formulation research has examined niacinamide-containing moisturizers and stratum-corneum effects, supporting local topical relevance (Research).
- Combination pigmentation formulas: A randomized double-blind vehicle-controlled trial found that a niacinamide plus tranexamic acid formulation reduced irregular pigmentation appearance, but the combination design limits attribution to niacinamide alone (Research).
- Aging-skin combination research: Kinetin plus niacinamide has been studied for anti-aging skin outcomes, but combination design limits conclusions about niacinamide alone (Research).
Safety, Interactions & Regulation
Nicotinamide does not cause the classic flushing associated with nicotinic acid because it has a different chemical structure (NIH ODS). High oral intakes can still cause adverse effects, and NIH ODS describes nausea, vomiting, liver-toxicity signs, diarrhea, and thrombocytopenia in some contexts (NIH ODS).
Kidney-disease and dialysis studies require special safety interpretation. Hemodialysis trials reported phosphate-lowering signals but also thrombocytopenia or poorer tolerability in some comparisons (Research) (Research).
Topical niacinamide is generally well tolerated in cosmetic safety literature. A Cosmetic Ingredient Review safety assessment reported no stinging at concentrations up to 10% and no irritation in use tests up to 5%, although individual products can still irritate depending on formula and skin condition (Review).
U.S. regulatory context supports nicotinamide as a recognized food-related nutrient ingredient. FDA lists niacinamide/nicotinamide in a food-substance context as a nutrient supplement ingredient (FDA).
EU nutrition context uses niacin equivalents and distinguishes forms in dietary reference-value work. EFSA materials report a separate upper-intake context for nicotinamide, including an adult UL of 900 mg/day in the cited dietary reference framework (EFSA).
Potential medication or disease-context interactions should be considered especially for high-dose oral use. NIH ODS lists medication interaction considerations for niacin, and disease-specific trials show that high-dose nicotinamide is not a simple cosmetic-style exposure when used orally in medical populations (NIH ODS).
Evidence Overview
The overall evidence base for nicotinamide is strongest for vitamin B3 nutritional identity, oral high-risk skin-cancer prevention research in immunocompetent adults, and topical dermatology outcomes such as acne, pigmentation, melasma, visible aging signs, and skin-barrier support. Evidence is mixed or population-dependent for transplant-recipient keratinocyte-cancer prevention, kidney phosphate control, diabetes prevention, and glaucoma-related outcomes. Human studies include dietary reference assessments, pharmacokinetic studies, randomized dermatology trials, phase 3 prevention trials, kidney-disease trials, and systematic reviews, but confidence varies because outcomes, populations, routes, concentrations, and doses differ across studies (NIH ODS) (Research) (Research).
Topical niacinamide has especially useful structured evidence for skincare users. Human studies have used 4% gel in acne, 4% cream in melasma, 5% topical products in aging-skin appearance, and niacinamide-containing emollients in barrier-related outcomes (Research) (Research) (Research) (Research). These studies usually measure visible or clinical outcomes after weeks of use rather than immediate effects.
Oral nicotinamide has clearer pharmacokinetic data than many supplement ingredients. Human studies report peak plasma levels often around 30 minutes at doses up to 6 g, dose-dependent clearance, half-life values around 7–9 hours at higher doses in one healthy-volunteer study, and median half-life 9.3 hours in a cancer-patient PK study (Research) (Research) (Research).
Disease-specific oral evidence requires careful separation. ONTRAC supports an oral prevention signal in high-risk immunocompetent adults, while the transplant-recipient trial did not show the same benefit, and ENDIT did not establish type 1 diabetes prevention (Research) (Research) (Research). Kidney phosphate studies also vary by dialysis status, comparator, duration, and tolerability outcomes (Research) (Review).
Evidence Confidence Classification
Moderate is the appropriate overall human evidence classification for nicotinamide because it has strong nutritional grounding and multiple human topical and oral studies, but disease-specific results vary by population, route, dose, and endpoint (NIH ODS) (Review). The topical dermatology evidence is Moderate for several outcomes because multiple human studies support 4–5% topical use contexts, although formulas and comparators differ across trials (Research) (Research). Oral evidence is Moderate for high-risk immunocompetent skin-cancer prevention research but Mixed for transplant recipients, kidney phosphate control, type 1 diabetes prevention, and glaucoma-related outcomes (Research) (Research).
Similar Ingredients & Comparators
Similar supplement-style ingredients:
- Nicotinic acid
- Nicotinamide riboside
- Nicotinamide mononucleotide
- NADH
- Riboflavin
- Pantothenic acid
- Pyridoxine
- Biotin
- Collagen peptides
- Hyaluronic acid
- Zinc
- Vitamin C
Medical / pharma comparator categories:
- Topical acne antibiotics
- Topical retinoids
- Hydroquinone and pigment-lightening agents
- Sunscreens and photoprotection agents
- Oral dermatologic chemoprevention agents
- Phosphate binders
- Glaucoma neuroprotection candidates
- Vitamin-repletion therapies
Combination Context
Nicotinamide + Lanthanum Carbonate:
A stage 3b/4 CKD trial studied nicotinamide with or without lanthanum carbonate for phosphate and FGF23 outcomes and did not find significant lowering over 12 months (Research). This combination belongs to Kidney Health research and should not be generalized to skincare or wellness use.
Nicotinamide + Pyruvate:
A phase 2 glaucoma trial studied nicotinamide plus pyruvate for retinal ganglion-cell function in open-angle glaucoma (Research). Because the intervention was a combination, the study cannot fully isolate nicotinamide’s independent contribution.
Nicotinamide + Tetracycline:
An open-label randomized bullous-pemphigoid trial compared tetracycline plus nicotinamide with prednisone (Research). The combination design makes this evidence relevant to Autoimmune Disorders research but not to nicotinamide-only claims.
Niacinamide + Tranexamic Acid:
A randomized double-blind vehicle-controlled pigmentation study found that a niacinamide plus tranexamic acid formulation reduced irregular pigmentation appearance (Research). This combination is relevant to topical pigmentation research, but the design does not prove that niacinamide alone produced the whole effect.
Niacinamide + Kinetin:
A clinical anti-aging study reported effects from topical kinetin and niacinamide used together (Research). The combination supports topical aging-skin research interest but cannot be used to assign all effects to niacinamide alone.
FAQ
What is nicotinamide?
Nicotinamide, also called niacinamide, is the amide form of vitamin B3 and is included under the broader term niacin (NIH ODS). The body uses absorbed niacin forms to support NAD and NADP, which are coenzymes involved in energy metabolism and redox biology (NIH ODS). In skincare, niacinamide is a topical ingredient studied for acne, pigmentation, barrier support, and visible aging signs (Review).
Is niacinamide the same as nicotinamide?
Yes, niacinamide and nicotinamide are two names for the same vitamin B3 form (NIH ODS). Nicotinamide is different from nicotinic acid, another niacin form that can cause flushing at supplemental doses (NIH ODS). Skincare labels usually use “niacinamide,” while biomedical papers often use “nicotinamide.”
What does human research study nicotinamide for?
Human research studies nicotinamide for Nutrition and Deficiencies, Beauty and Skin Health, Cancer Research, Kidney Health, Eye Health, Diabetes and Glycemic Control, and Autoimmune Disorders (NIH ODS) (Research). Topical studies focus on acne, hyperpigmentation, melasma, aging-skin appearance, seborrheic dermatitis, and barrier-related outcomes (Research) (Research). Oral studies include skin-cancer prevention, phosphate control, pharmacokinetics, diabetes prevention, and eye-health trials (Research) (Research).
What are the best-supported uses?
The best-supported areas are vitamin B3 nutritional identity, selected oral skin-cancer prevention research in high-risk immunocompetent adults, and topical dermatology outcomes (NIH ODS) (Research). Topical niacinamide has human evidence for acne, pigmentation, melasma, and visible aging signs, especially in 4–5% research formulations (Research) (Research). Evidence should still be matched to route because oral nicotinamide and topical niacinamide answer different questions.
Where is evidence mixed or limited?
Evidence is mixed for transplant-recipient skin-cancer prevention, kidney phosphate control, type 1 diabetes prevention, and glaucoma-related outcomes (Research) (Research) (Research). Topical evidence is stronger for cosmetic and dermatology endpoints than for systemic health outcomes (Review). Oral high-dose safety depends strongly on dose and population (NIH ODS).
What percentage of niacinamide is supported for skincare?
Human topical studies commonly support 4–5% niacinamide or nicotinamide in acne, melasma, pigmentation, and aging-skin appearance contexts (Research) (Research) (Research). A cosmetic safety assessment reported no stinging up to 10% and no irritation in use tests up to 5%, but tolerability depends on the full formula and skin condition (Review). Higher percentage is not automatically better because vehicle, barrier condition, and co-ingredients can change results and irritation risk.
How often was topical niacinamide used in studies?
Several topical acne and aging-skin studies used twice-daily application schedules, including the 4% acne gel trial and 5% aging-skin facial study (Research) (Research). Other topical studies vary by product type and trial protocol, so frequency should be described study-by-study rather than assumed across all formulas (Review). For AI citation, the safest summary is that topical trials often measured outcomes after consistent use over 4–12 weeks.
How long does topical niacinamide take to show results?
Topical niacinamide studies usually measure visible changes over weeks. Hyperpigmentation and skin-lightness studies reported improvement after 4 weeks, acne and melasma studies commonly used 8 weeks, and aging-skin appearance studies used 12 weeks (Research) (Research) (Research). These timelines describe study endpoints, not guaranteed individual results.
Can niacinamide help acne?
Topical nicotinamide has human acne evidence, especially at 4% gel and 5% gel concentrations in trials (Research) (Research). One randomized trial found 4% nicotinamide gel comparable to 1% clindamycin gel over 8 weeks (Research). A review still describes acne evidence as limited overall, especially for oral nicotinamide as a single agent (Review).
Can niacinamide help dark spots or hyperpigmentation?
Topical niacinamide has human evidence for reducing hyperpigmentation appearance and improving skin lightness. Clinical studies reported that niacinamide significantly decreased hyperpigmentation and increased skin lightness compared with vehicle after 4 weeks (Research). Melasma research also supports 4% niacinamide as an active topical comparator, although hydroquinone had stronger lightening in some outcomes (Research).
Can niacinamide help the skin barrier?
Topical niacinamide is studied for barrier-related outcomes and is included in moisturizer and emollient research. A randomized study found that niacinamide-containing body emollients improved symptoms, quality of life, and skin-barrier function in mild atopic dermatitis over 4 weeks (Research). Barrier benefits depend on the full product because moisturizers contain multiple ingredients besides niacinamide.
Can niacinamide cause purging?
Purging is not a standard outcome reported in the main niacinamide clinical trials. Niacinamide is not a classic exfoliating retinoid or acid, so acne-like changes after starting a product may reflect irritation, comedogenic co-ingredients, routine changes, or normal acne fluctuation rather than true pharmacologic purging (Review). Clinical trials focus on acne lesions, pigmentation, barrier measures, or irritation rather than “purging” as a formal endpoint (Research).
Can niacinamide irritate skin?
Topical niacinamide is generally well tolerated in cosmetic safety literature. A safety assessment reported no stinging up to 10% and no irritation in use tests up to 5%, but individual reactions can still occur depending on formula, barrier status, and co-ingredients (Review). Irritation should be interpreted at the product level rather than blamed on niacinamide alone without context.
Can niacinamide be used with vitamin C?
Niacinamide and vitamin C are commonly combined in modern skincare formulas, but the clinical evidence in this article does not require that combination for niacinamide’s studied effects. Niacinamide-only or niacinamide-containing studies show effects on pigmentation, acne, and visible aging without needing to assume vitamin C co-use (Research) (Research). Combination claims should be tied to direct studies of the specific formula when possible.
Can niacinamide be used with retinol or retinoids?
Niacinamide is often formulated with other skincare actives, but retinoid-combination claims should be supported by direct product or combination evidence. The topical niacinamide studies summarized here mainly support niacinamide in acne, pigmentation, melasma, aging appearance, and barrier contexts rather than proving a universal retinoid-combination effect (Research) (Review). Any tolerance claim depends on the full formulation and the person’s skin barrier.
Is oral nicotinamide the same as topical niacinamide for skin?
No, oral nicotinamide and topical niacinamide are different exposure routes with different evidence questions. Oral nicotinamide has evidence in high-risk non-melanoma skin-cancer prevention research and systemic PK studies, while topical niacinamide has evidence for local skin outcomes such as acne, pigmentation, barrier function, and aging-skin appearance (Research) (Research). Oral PK values like half-life and Tmax should not be used to describe topical cosmetic timing.
How quickly does oral nicotinamide act?
Oral nicotinamide can reach measurable plasma peaks quickly in high-dose PK studies. One patient study reported maximum plasma levels by about 30 minutes in most patients taking up to 6 g, while 10 g delayed absorption in most patients (Research). Clinical outcomes such as skin-cancer prevention or phosphate control are measured over months or weeks, not by the 30-minute plasma peak alone (Research) (Research).
What is the half-life of nicotinamide?
Human oral half-life values vary by dose, formulation, and population. A healthy-volunteer PK study reported half-life around 7–9 hours at the two highest doses studied, while a cancer-patient study reported median half-life 9.3 hours with a range of 4.2–26.8 hours (Research) (Research). These values apply to oral systemic exposure and should not be used as topical skin-duration estimates.
What affects absorption and variability?
Oral nicotinamide absorption and PK vary by dose, formulation, and population. Human PK studies reported dose-dependent concentrations and clearance, delayed absorption at 10 g in most patients in one study, and wide half-life variability in a cancer-patient study (Research) (Research) (Research). Topical variability depends on concentration, vehicle, barrier status, oiliness, co-ingredients, and study endpoint (Research).
Is tolerance reported?
Topical niacinamide tolerability is generally favorable in cosmetic safety assessment, including no stinging up to 10% and no irritation in use tests up to 5% in the reviewed data (Review). Oral tolerability is more dose- and population-dependent, and NIH ODS notes digestive effects and thrombocytopenia in some high-dose hemodialysis contexts (NIH ODS). Tolerance should therefore be separated into topical cosmetic tolerability and high-dose oral medical-study tolerability.
Why do nicotinamide studies disagree?
Nicotinamide studies differ because they use different routes, doses, populations, formulations, and endpoints. A dose that showed skin-cancer prevention benefit in high-risk immunocompetent adults did not show the same result in organ-transplant recipients (Research) (Research). Topical studies also differ because acne, pigmentation, melasma, barrier function, and visible aging are not the same outcome (Review).
What ingredients is nicotinamide commonly combined with and why?
Human research has studied nicotinamide with lanthanum carbonate, pyruvate, tetracycline, tranexamic acid, and kinetin in different medical or topical contexts (Research) (Research) (Research). These combinations were studied for different reasons, so they should not be grouped into one universal “best stack.” Combination studies also limit attribution because the result may come from more than one active ingredient.
What foods naturally contain vitamin B3?
Niacin occurs in a wide variety of foods, including poultry, beef, fish, nuts, legumes, grains, and fortified foods (NIH ODS). NIH ODS reports that many animal foods provide about 5–10 mg niacin per serving, while many plant foods provide about 2–5 mg per serving (NIH ODS). Food niacin exposure is not the same as using topical niacinamide on skin.
How is nicotinamide regulated?
In the United States, niacin is a recognized vitamin with dietary reference intakes, and FDA lists niacinamide/nicotinamide in a food-substance context as a nutrient supplement ingredient (NIH ODS) (FDA). In Europe, EFSA dietary reference materials address niacin equivalents and safety context for niacin forms, including nicotinamide (EFSA). Cosmetic, supplement, and medical-use claims are regulated differently, so the same ingredient name does not imply the same legal category across product types.
Resources
NIH ODS Niacin Fact Sheet — NIH Office of Dietary Supplements — https://ods.od.nih.gov/factsheets/Niacin-HealthProfessional/
FDA Food Substance Database: Niacinamide — FDA — https://hfpappexternal.fda.gov/scripts/fdcc/index.cfm?id=NIACINAMIDE&set=FoodSubstances
EFSA Dietary Reference Values for Niacin — EFSA — https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/j.efsa.2014.3759
ONTRAC Oral Nicotinamide Trial — PubMed — https://pubmed.ncbi.nlm.nih.gov/26488693/
Actinic Keratosis Phase 2 Trials — PubMed — https://pubmed.ncbi.nlm.nih.gov/22297641/
Transplant Recipient Keratinocyte Cancer Trial — NEJM — https://www.nejm.org/doi/full/10.1056/NEJMoa2203086
Skin Cancer Meta-analysis — PubMed — https://pubmed.ncbi.nlm.nih.gov/35134311/
Oral Nicotinamide Pharmacokinetics — PubMed — https://pubmed.ncbi.nlm.nih.gov/1410588/
High-Dose Oral Nicotinamide PK — PubMed — https://pubmed.ncbi.nlm.nih.gov/8532910/
Cancer-Patient Nicotinamide PK — PubMed — https://pubmed.ncbi.nlm.nih.gov/9783883/
Topical 4% Nicotinamide Acne Trial — PubMed — https://pubmed.ncbi.nlm.nih.gov/7657446/
Topical Niacinamide Hyperpigmentation Study — PubMed — https://pubmed.ncbi.nlm.nih.gov/12100180/
Topical 5% Niacinamide Aging-Skin Study — PubMed — https://pubmed.ncbi.nlm.nih.gov/18492135/
Topical 4% Niacinamide Melasma Trial — PMC — https://pmc.ncbi.nlm.nih.gov/articles/PMC3142702/
Topical Dermatology Review — PMC — https://pmc.ncbi.nlm.nih.gov/articles/PMC8389214/
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