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Ingredients
Niacinamide, explained: what it actually does and who it suits
One of the most-mentioned ingredients in skincare is also one of the better-evidenced ones. Here is the mechanism behind the marketing, and a realistic sense of what it changes.
Petal & Proof Editorial Team3 min readLast updated 8 August 2026
What niacinamide is
Niacinamide is a form of vitamin B3 (nicotinamide) used in skincare as a water-soluble active, most commonly in serums and moisturisers. It is stable, tolerates a wide pH range, and is inexpensive to formulate with, which is part of why it turns up across such a wide span of prices — in this dataset, serums tagged with niacinamide range from £5.69 (Simple Face Serum) up to £26.26 (Eucerin Overnight Face Serum), with Some By Mi's Face Serum at £20.18 sitting in between. A higher price here reflects packaging and brand more than a materially different ingredient.
The mechanism: barrier support and oil regulation
Niacinamide's best-supported effects come from two related jobs. It supports the skin's production of ceramides — the lipids that hold the outer barrier together — which is why it is often paired with barrier-focused claims. Separately, it appears to moderate sebum output in oily and combination skin, which is the mechanism behind claims about shine and the appearance of pores. Neither effect is dramatic or fast; both build with consistent use rather than appearing after a handful of applications.
What it is marketed for versus what holds up
Barrier support and oil moderation are the two claims with the most consistent backing. Claims about brightening and evening out tone are more modest in practice — niacinamide can help with the appearance of dullness and post-inflammatory marks over time, but it is not a substitute for sun protection or a targeted pigmentation ingredient, and it works slowly enough that a four-week trial tells you little.
Concentration is not a race to the highest number
Most of the research behind niacinamide uses concentrations in the region of 2% to 5%. Formulas advertising much higher percentages are not automatically more effective, and above roughly 5% some people notice flushing or a warm, tingling sensation — a niacinamide-specific irritation that is more about individual tolerance than product quality. If a serum you are using stings or flushes, dropping to a lower-percentage version or using it less often is a reasonable first step before assuming the ingredient does not suit you.
The vitamin C question
Niacinamide was historically said to clash with vitamin C, on the basis that combining them could convert niacinamide into niacin at low pH and cause flushing. Modern stabilised formulas have largely made this a non-issue for most people, and many serums now contain both deliberately. If your skin is reactive, using them at separate times of day (vitamin C in the morning, niacinamide at night, for example) removes the variable without giving up either ingredient.
How to actually add it to a routine
Niacinamide serums are applied after cleansing and before moisturiser, and the ingredient is gentle enough for daily use, morning or evening. As with most actives aimed at tone and texture rather than immediate hydration, judge it over eight to twelve weeks rather than days — that is roughly the timeframe skin takes to show a change, and judging earlier is the most common reason people abandon a product that would otherwise have worked.
Serums to consider
Real face-serum listings on Amazon UK, several of which carry a niacinamide tag in this dataset — see the full face serums page for the complete, sortable list including other actives.
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- Rated 3.8 out of 5 from 431 reviews
- Rated 4.8 out of 5 from 16 reviews
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Related products
More real listings on Amazon UK related to this article. See the full face serums page for the complete, sortable list.
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- Rated 3.9 out of 5 from 24 reviews
fragrance-free
- fragrance-free
Frequently asked questions
- Can I use niacinamide every day?
- Yes. It is one of the gentler actives and is generally well tolerated at daily use, morning or evening, unlike stronger exfoliating acids or retinoids that need a slower introduction.
- Does niacinamide actually shrink pores?
- Not physically — pore size is largely fixed by genetics and skin structure. What niacinamide can do is moderate oil production, which reduces how visible pores appear, particularly on oily and combination skin. That is a real, if more modest, effect than the phrase "shrinks pores" implies.
- Can I use niacinamide with vitamin C?
- In most modern formulas, yes. The older advice to avoid combining them came from older, less stable formulations. If your skin is sensitive, using one in the morning and the other at night avoids the question entirely.
- How long before niacinamide does anything visible?
- Consistent daily use for eight to twelve weeks is a realistic window for tone and oiliness changes. Any barrier-support benefit builds gradually in the background rather than announcing itself.
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Petal & Proof Editorial Team
We do not test products hands-on — see our editorial policy for how listings are sourced and ranked.
Last updated 8 August 2026 · 646 words