TL;DR: Niacinamide quietly does six jobs: barrier repair, oil control, redness, pigment, pore look, fine lines. 5% is the workhorse; 10% has diminishing returns.
Quick answer
Niacinamide (vitamin B3) is one of the few skincare ingredients with strong evidence across multiple categories: barrier repair, oil regulation, redness, hyperpigmentation, pore appearance. 5% is the well-studied workhorse concentration. 10% is fine for most skin and offers diminishing returns above that. It pairs with virtually everything, including vitamin C — the old “they cancel each other out” line has been pretty definitively debunked. It’s probably the single most flexible active in modern skincare.
What niacinamide does
Inside your skin, niacinamide converts to NAD+ and NADP+, two coenzymes that are involved in dozens of cellular processes. Topically, that translates to a few measurable effects.
Barrier reinforcement. Niacinamide stimulates ceramide synthesis, strengthening the lipid mortar that holds the barrier together. Studies show measurable reduction in transepidermal water loss within four weeks.
Sebum regulation. Niacinamide reduces excess sebum production in clinical trials. Useful for oily and combination skin without the stripping effect of harsher oil-control ingredients.
Hyperpigmentation. It blocks the transfer of melanin from melanocytes to keratinocytes — different mechanism from vitamin C’s tyrosinase inhibition. Which is why the two compound when used together.
Redness and inflammation. Strong evidence for reducing erythema in rosacea-prone and reactive skin.
Pore appearance. Pores look smaller after a few weeks of consistent use, primarily because the skin around them is firmer and the sebum is cleaner. Not because pores have shrunk (they can’t). But the visual result is real.
Fine line softening. Modest evidence for visible reduction in fine lines over months of use, likely via collagen-supportive effects.
The 5% vs 10% debate
The skincare internet has spent years arguing about whether 10% is meaningfully better than 5%, and whether high concentrations cause flushing.
The evidence: 5% is the most-studied concentration and reliably produces the documented benefits. 10% gives slightly better results on some metrics with a higher rate of mild irritation. Above 10%, returns diminish and irritation risk climbs. Some Korean formulations push 12–15%; that’s not where the science lives.
Practical version: start with 5%. Move to 10% if your skin tolerates it and you want a stronger product. Don’t pay premium prices for 12%-plus.
The vitamin C myth
The internet has been telling people for years that vitamin C and niacinamide cancel each other out. That comes from a 1960s study where pure niacinamide and pure ascorbic acid were combined in solution, and a small amount converted to nicotinic acid (which causes flushing).
In modern skincare formulations, with stabilizers, proper pH, and skin-level absorption, the conversion is negligible. Multiple recent studies show no antagonism. You can use vitamin C and niacinamide in the same routine, in the same product, on the same skin, without losing benefit.
The only caveat: very high concentrations of pure L-ascorbic acid plus very high concentrations of niacinamide in a poorly buffered formulation can produce mild flushing for some people. If you notice that, separate them by routine (vitamin C in the morning, niacinamide at night). Otherwise, layer freely.
Who should use niacinamide
Almost everyone. It’s one of the few ingredients with a defensible case for nearly every skin type.
Oily skin gets sebum regulation. Acne-prone skin gets anti-inflammatory support and barrier reinforcement during acne treatment. Sensitive skin gets gentle barrier repair and reduced redness. Mature skin gets ceramide synthesis and modest fine-line softening. Hyperpigmented skin gets tone evening, especially when paired with vitamin C or tranexamic acid. Rosacea-prone skin gets redness reduction (with derm guidance).
The exception is a small group of people who genuinely flush from topical niacinamide (the “niacin flush” reaction some get from oral B3). If your skin reliably goes red after applying it, that’s a real reason to skip. Though most people who think they have this actually have a damaged barrier or a fragrance reaction in the formulation.
How to use it
Time of day: either AM or PM. It’s stable and well-tolerated at any time.
Order: as a serum, after cleansing and toning, before moisturizer. As an ingredient in a moisturizer or essence, layer normally.
Concentration: start at 5%. Move to 10% only if 5% isn’t doing what you want.
Frequency: daily is fine. Twice daily is fine for most skin types.
Pairing: niacinamide gets along with retinoids (reduces irritation), AHAs and BHAs (calms inflammation), peptides, ceramides, hyaluronic acid, vitamin C, and SPF. Effectively every standard ingredient in modern skincare.
What niacinamide can’t do
It isn’t a magic bullet for any single concern. It won’t substitute for SPF in pigmentation prevention. It won’t substitute for retinoids in serious anti-aging. It won’t clear cystic or hormonal acne on its own. And it won’t repair a severely damaged barrier as a sole intervention — ceramides are still the priority there.
It’s a rising-tide-lifts-all-boats ingredient. Strong supporting actor, rarely the lead.
Where people go wrong
Skipping it because the routine is “already complete.” Niacinamide adds barrier benefits to almost any routine without requiring you to remove anything.
Buying the highest concentration on the shelf. 12–20% products are usually marketing and more likely to irritate.
Expecting visible pore shrinkage. Pores don’t actually shrink. The smaller-looking result is real but it comes from firmer surrounding skin and cleaner sebum, not from physical pore size.
Using a niacinamide serum and a niacinamide moisturizer at the same time. No real harm, but you’re paying for the same active twice.
FAQ
Can I use niacinamide every day, forever? Yes. No tolerance, no rebound, no need to cycle off.
Does niacinamide cause purging? Rarely. It doesn’t accelerate cell turnover the way retinoids and acids do, so it doesn’t trigger the classic purge.
What’s the difference between niacinamide and nicotinic acid? Niacinamide is the amide form of nicotinic acid. Both are vitamin B3, but they behave differently topically and orally. Skincare uses niacinamide. Nicotinic acid is the form behind the famous oral flushing reaction.
Is The Ordinary’s 10% niacinamide + 1% zinc enough? It’s a perfectly good product. The zinc adds modest additional sebum control. Plenty of readers’ niacinamide journey starts there and never needs anything else.
Sources
Hakozaki T et al. The effect of niacinamide on reducing cutaneous pigmentation. British Journal of Dermatology, 2002. Bissett DL et al. Niacinamide: a B vitamin that improves aging facial skin appearance. Dermatologic Surgery, 2005.
Keep reading
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