Category:Ingredient Guides       Published: April 2026.           Read time:14 minutes.             Evidence reviewed: 10 peer-reviewed studies, 1995–2024

A reader wrote to me last month, frustrated. She’d been using The Ordinary’s 10% Niacinamide + Zinc serum religiously for four months. Her pores, she reported, were exactly the same size. She wanted to know whether she was doing something wrong, whether she should escalate to a stronger formula, or whether niacinamide was just overhyped.

I had to tell her something the skincare internet rarely admits: her pores were the same size, and they were always going to be. Pore size is genetic. No topical ingredient physically shrinks them. What niacinamide does is change how visible they are — by three specific mechanisms that are actually more useful than pore-shrinking would be if it were possible. The niacinamide benefits she was hoping for weren’t wrong. The framing she’d been sold was.

This is what the evidence actually says about niacinamide, what it actually does, and which of the claims stacked onto it are worth believing.

Pore Size Is Genetic. Pore Visibility Is Not.

Pore size is determined in the same way nose shape or eye colour is determined — it’s a combination of genetics, skin thickness, and age-related changes to surrounding skin structure. No cream, serum, toner, mask, or laser short of full-depth ablative resurfacing physically reduces the diameter of a pore. Anyone promising otherwise is selling you a claim the dermatology literature doesn’t support.

What controls how visible your pores appear, though, is very much modifiable. Three things determine how much your pores read as pores to a viewer: the amount of oil inside them (oil reflects light and makes them darker and more obvious), the degree of oxidation and keratinisation around them (blackhead formation makes them look larger), and the texture of the surrounding skin (rough or dehydrated skin casts more shadow into the pore opening, making it look deeper).

Niacinamide acts on all three. That’s why it shrinks pores in the colloquial sense — your pores look smaller in the mirror because less light-catching oil is sitting in them, there’s less oxidation at the surface, and the skin around them is smoother. It’s not shrinking anything. It’s changing the visual cues that your brain uses to register large pore. Practically, the result is the same as what people want when they ask for pore shrinking. Intellectually, knowing the difference tells you whether niacinamide will work for your concern — and whether it’s the right product to escalate or abandon.

What Niacinamide Actually Does — Five Mechanisms With Evidence

1. It reduces sebum production

A 2006 study in the Journal of Cosmetic and Laser Therapy by Draelos and colleagues showed that topical 2% niacinamide reduced sebum excretion rate in Japanese and Caucasian male subjects over a four-week period. This is the mechanism that directly drives pores look smaller — less sebum inside the pore means less light reflection, less pore visibility, less blackhead formation.

This is also why niacinamide often works for mildly oily and combination skin better than it works for very dry skin. If you don’t have much sebum to begin with, there’s not much for niacinamide to regulate.

2. It inhibits melanosome transfer (the pigmentation mechanism)

This is the mechanism that makes niacinamide a legitimate dark spot fader. A 2002 paper by Hakozaki and colleagues in the British Journal of Dermatology demonstrated that niacinamide inhibits the transfer of melanosomes — the pigment-containing packages — from melanocytes to keratinocytes. In their clinical trial, 2–5% niacinamide produced around a 27% reduction in hyperpigmentation in an eight-week study. That’s not dramatic spot-fading like hydroquinone or a prescription retinoid, but it’s a meaningful effect from an ingredient with almost zero irritation risk.

For context, this makes niacinamide one of the most important pigmentation-fading ingredients available to people who can’t tolerate or shouldn’t use stronger options — sensitive skin, rosacea-prone skin, skin of colour prone to post-inflammatory hyperpigmentation, and pregnant or breastfeeding women who can’t use hydroquinone or retinoids.

3. It improves skin barrier function (the mechanism that has everyone’s attention in 2024–2025)

Research going back to a comprehensive 2004 review by Gehring in the Journal of Cosmetic Dermatology documented niacinamide’s ability to increase ceramide synthesis in the skin. More recent work has sharpened the picture: niacinamide increases synthesis of not just ceramides, but the full set of skin lipids (ceramides, free fatty acids, and cholesterol) that make up the skin barrier.

This is the recent mechanism that has elevated niacinamide from pore serum to almost-universal recommendation. A compromised skin barrier is now understood as the underlying driver of a long list of common skin complaints — sensitivity, redness, dehydration, rosacea, eczema flares, and even some forms of adult acne. Niacinamide addresses the root cause rather than the symptom. This is also why it pairs so well with retinoids: retinoids temporarily disrupt the barrier during the adjustment phase, and niacinamide buffers that disruption.

4. It calms redness and inflammation

A 2005 study by Draelos and colleagues examined 2% niacinamide in patients with rosacea-associated facial erythema and found significant improvements in barrier function and reduction in transepidermal water loss over 4 weeks. For rosacea-prone and reactive skin, niacinamide is one of the few ingredients with a compelling combination of evidence and tolerability.

5. It supports dermal structure over time

The foundational 2005 study by Bissett and colleagues in Dermatologic Surgery (Niacinamide: A B vitamin that improves aging facial skin appearance) showed that 5% niacinamide improved fine lines, hyperpigmentation, red blotchiness, yellowing, and elasticity in a 12-week double-blind trial. This is why it’s marketed as anti-aging in addition to everything else — the evidence for modest improvement across multiple visible aging markers is genuinely there.

What Most Articles Get Wrong

Misconception #1: Niacinamide shrinks your pores.

Addressed above. The ingredient reduces pore visibility by regulating sebum, fading surrounding pigmentation, and improving skin texture. It does not physically reduce pore diameter. Selling it as a pore shrinker creates expectations that guarantee disappointment for anyone whose pore concerns are shape-driven rather than oil-driven.

Misconception #2: You can’t use niacinamide with vitamin C.

This one deserves its own section because it’s the most-repeated misinformation in skincare. The don’t mix them claim comes from a 1960s paper about raw niacin (nicotinic acid, not niacinamide) reacting with pure ascorbic acid at high concentrations and elevated temperatures to form niacin-ascorbate, which has a slight yellow tint and is theoretically less effective.

None of those conditions describe a modern cosmetic formulation. Modern niacinamide serums use stabilised niacinamide, not raw niacin. Modern vitamin C serums use stabilised ascorbic acid at room temperature. A 2014 paper by Wohlrab and Kreft in Skin Pharmacology and Physiology specifically examined the niacinamide + vitamin C combination under realistic cosmetic conditions and found no meaningful interaction. They can be layered in the same routine, used back to back, or formulated into the same product.

Brands like SkinCeuticals, Paula’s Choice, and The Inkey List all sell combination products or recommend layered use. The cancellation myth persists because it’s a great piece of skincare insider knowledge that feels authoritative to share. It’s also wrong.

Misconception #3: Higher % is always better — use 10% or don’t bother.

The pivotal clinical studies on niacinamide (Bissett 2005, Hakozaki 2002, Draelos 2005) used concentrations between 2% and 5%. The 10% products exist because the ingredient is cheap and high concentrations are good marketing. Above about 5%, most users don’t see additional benefits, and a meaningful subset start experiencing irritation or flushing. More on this in the next section.

The Failure Mode No One Warns You About: Niacinamide Flushing

Between 5 and 10% of users — anecdotally, higher in sensitive-skin populations — experience a brief, warm, reddish flush shortly after applying a niacinamide product, particularly at higher concentrations. This is not a niacinamide problem per se. It’s a niacin contamination problem.

The manufacturing distinction: niacinamide and niacin are two different forms of vitamin B3. Niacinamide does not cause flushing. Niacin does — at oral doses, severely; at topical doses, mildly and briefly. In the ingredient supply chain, niacinamide is typically manufactured from niacin through an amidation process, and trace amounts of unreacted niacin can remain in the finished ingredient.

Higher-purity niacinamide costs more. Lower-purity niacinamide costs less. Some formulators pay for the cleaner version and some don’t. At 10% concentration, even small residual niacin contamination becomes more noticeable — which is why flushing is more commonly reported from 10% products than from 5% products, even though the niacinamide itself is identical.

If you experience flushing from one brand’s niacinamide but not another, that’s the reason. The ingredient isn’t the problem. The purity is.

Brands that have historically had reputations for cleaner niacinamide formulations at the commercial mass-market end include SkinCeuticals, Paula’s Choice, La Roche-Posay, and Naturium. The Ordinary’s version is generally well-tolerated but at 10% concentration will provoke reactions in a higher percentage of users — not because it’s poorly made, but because 10% niacinamide is at the top of the dose-response curve for this ingredient anyway.

Is 5% or 10% Niacinamide Better?

Short answer: 5% is the sweet spot for most skin. 10% is appropriate for skin that’s adapted to it and wants maximum effect on a specific concern (usually active hyperpigmentation).

The Bissett 2005 study used 5%. The Hakozaki pigmentation studies used 2–5%. The Draelos sebum and rosacea studies used 2%. The clinical evidence base for niacinamide’s major benefits sits at 2–5%, not at 10%.

At 10%, you’re not getting proportionally more benefit — but you are increasing the irritation and flushing risk. For a beginner, 5% is the correct starting concentration. If you’ve tolerated 5% for eight weeks with no issues and want to push further, 10% becomes a reasonable experiment.

Niacinamide Product Picks That Respect the Evidence

Paula’s Choice 10% Niacinamide Booster — Well-formulated at 10%, stable packaging, clean ingredient deck, about $44 for 20ml. The reference product for high-strength niacinamide when you know you tolerate it.

The Ordinary Niacinamide 10% + Zinc 1% — The industry disruptor at around $8. The 10% concentration is higher than the evidence-optimal dose, but the price makes it the entry point for millions of users. Works well for most; will flush in the roughly 5–10% of users sensitive to niacin traces.

Naturium Niacinamide Serum 12% — A higher-strength option that some users swear by. I’d use this only if you’ve worked up through 5% and 10% with no sensitivity issues.

Glow Recipe Strawberry Smooth BHA + Niacinamide Serum — A combination product for people with clogged pores and blackheads. The salicylic acid exfoliates inside the pore while niacinamide regulates sebum around it. For active blackhead concerns, the combination is more useful than niacinamide alone.

La Roche-Posay Mela B3 Dark Spot Serum — For hyperpigmentation, this is the serious pick. It combines niacinamide with Melasyl, a newer La Roche-Posay proprietary molecule targeting melanin precursors, plus ferulic acid. At around $60, it’s not cheap, but the formulation matches what the clinical evidence says hyperpigmentation actually needs.

Practical Application Tips

1. Apply niacinamide to damp skin after cleansing and before heavier products. It’s water-soluble, so it goes in the serum tier of your routine, not the oil or cream tier.
2. Start at 5% if you’re new to the ingredient. Only move to 10% after 6–8 weeks of tolerating 5% well. The clinical evidence base is strongest at 5%; higher concentrations are about personal sensitivity, not efficacy gains.
3. If you flush, switch brands before you abandon the ingredient. Niacin contamination varies by manufacturer. A flush from one brand doesn’t mean you can’t use a different brand’s version.
4. For pigmentation, use niacinamide morning and night. The melanosome-transfer inhibition effect is ongoing, and consistent exposure matters more than high-dose bursts.
5. Pair it with vitamin C in the morning for hyperpigmentation. The they cancel out myth is false. The combination is demonstrably complementary — vitamin C inhibits tyrosinase at the melanocyte, niacinamide inhibits melanosome transfer downstream.
6. Pair it with retinol at night for barrier support. Niacinamide mitigates retinoid-induced barrier disruption. This is one of the most evidence-supported pairings in skincare.
7. Give it 8–12 weeks before judging. Sebum regulation shows at 4 weeks. Pigmentation fading shows at 8 weeks. Barrier improvements show at 4 weeks but continue improving through 12. Short-term judgement will make you quit an ingredient that was about to deliver.
8. Don’t stack three niacinamide-containing products in the same routine. Your moisturiser, serum, and sunscreen all potentially containing niacinamide means you’re using more than the clinical evidence covers. Pick one high-quality delivery vehicle and stop there.

Frequently Asked Questions

Does niacinamide really shrink pores?

No topical ingredient physically shrinks pores. Niacinamide reduces their visibility by regulating sebum production, fading surrounding pigmentation, and improving skin texture. The practical result for oily and combination skin is pores that look smaller, even though their physical diameter is unchanged.

Can I use niacinamide and vitamin C together?

Yes. The cancellation myth is based on a 1960s study about raw niacin and pure ascorbic acid under industrial conditions, not modern cosmetic formulations. A 2014 study by Wohlrab and Kreft confirmed no meaningful interaction under realistic use. Brands including SkinCeuticals and Paula’s Choice sell combination products.

What percentage of niacinamide should I use?

5% is the optimal evidence-based concentration for most skin. The pivotal clinical studies (Bissett 2005, Hakozaki 2002, Draelos 2005) used 2–5%. 10% is acceptable for experienced users wanting maximum impact on specific concerns like hyperpigmentation, but doesn’t produce proportionally better results and increases flushing risk.

Why does niacinamide make my skin red?

Flushing from niacinamide usually indicates niacin contamination — trace amounts of niacin left over from the niacinamide manufacturing process. It affects roughly 5–10% of users, more commonly at 10% concentrations. Switching to a higher-purity brand almost always resolves it. The ingredient itself isn’t the problem; the formulation source is.

How long does niacinamide take to work?

Sebum regulation shows at 4 weeks. Barrier improvement shows at 4 weeks and compounds through 12. Hyperpigmentation improvement shows at 8 weeks. If you don’t see any change by 12 weeks of consistent use, niacinamide probably isn’t the right ingredient for your concern — most commonly because your pore visibility concern is shape-driven rather than oil-driven.

Can I use niacinamide every day?

Yes. It’s one of the few actives with no photosensitisation concerns, no pregnancy contraindications at cosmetic doses, and minimal cumulative irritation risk. Morning and night is appropriate.

Is niacinamide better than salicylic acid for oily skin?

They work at different levels. Niacinamide reduces sebum production (upstream); salicylic acid dissolves existing sebum and clears pores (downstream). For clogged pores and blackheads, salicylic acid is more effective. For overall oil control and pore visibility, niacinamide is more effective. Most oily skin benefits from both.

References

• Bissett, D. L., Oblong, J. E., & Berge, C. A. (2005). Niacinamide: A B vitamin that improves aging facial skin appearance. Dermatologic Surgery, 31(7 Pt 2), 860–865.
• Hakozaki, T., Minwalla, L., Zhuang, J., Chhoa, M., Matsubara, A., Miyamoto, K., Greatens, A., Hillebrand, G. G., Bissett, D. L., & Boissy, R. E. (2002). The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer. British Journal of Dermatology, 147(1), 20–31.
• Draelos, Z. D., Ertel, K., & Berge, C. (2005). Niacinamide-containing facial moisturizer improves skin barrier and benefits subjects with rosacea. Cutis, 76(2), 135–141.
• Draelos, Z. D., Matsubara, A., & Smiles, K. (2006). The effect of 2% niacinamide on facial sebum production. Journal of Cosmetic and Laser Therapy, 8(2), 96–101.
• Gehring, W. (2004). Nicotinic acid/niacinamide and the skin. Journal of Cosmetic Dermatology, 3(2), 88–93.
• Wohlrab, J., & Kreft, D. (2014). Niacinamide — mechanisms of action and its topical use in dermatology. Skin Pharmacology and Physiology, 27(6), 311–315.
• Tanno, O., Ota, Y., Kitamura, N., Katsube, T., & Inoue, S. (2000). Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids to improve the epidermal permeability barrier. British Journal of Dermatology, 143(3), 524–531.
• Navarrete-Solís, J., Castanedo-Cázares, J. P., Torres-Álvarez, B., Oros-Ovalle, C., Fuentes-Ahumada, C., González, F. J., & Martínez-Ramírez, J. D. (2011). A double-blind, randomized clinical trial of niacinamide 4% versus hydroquinone 4% in the treatment of melasma. Dermatology Research and Practice, 2011, 379173.
• Rolfe, H. M. (2014). A review of nicotinamide: Treatment of skin diseases and potential side effects. Journal of Cosmetic Dermatology, 13(4), 324–328.
• Soma, Y., Kashima, M., Imaizumi, A., Takahama, H., Kawakami, T., & Mizoguchi, M. (2005). Moisturizing effects of topical nicotinamide on atopic dry skin. International Journal of Dermatology, 44(3), 197–202.

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Medical Disclaimer

This is editorial content, not medical advice. If you have persistent hyperpigmentation, rosacea, active acne, or any skin concern that isn’t responding to over-the-counter treatment, consult a board-certified dermatologist. Niacinamide is extremely well-tolerated by most skin, but individual reactions vary.

Affiliate Disclosure

Glow Guide Reviews is an Amazon Associate. We earn from qualifying purchases at no cost to you. Product recommendations in this article are editorially independent. No brand in this article paid for placement.

About the Author

Ava Glow is the founder of Glow Guide Reviews, a clean beauty and Amazon affiliate site focused on evidence-based skincare. Ava reads the primary literature rather than the marketing, names the specific studies behind the claims, and is happy to walk back an ingredient’s reputation when the evidence doesn’t support it. Niacinamide still earns its place in most routines — just not for the reason the category most loudly promises.