Niacinamide — also known as Vitamin B3 or nicotinamide — is the most versatile single ingredient in skincare. Clinical studies support its ability to reduce pore appearance, control sebum production, fade hyperpigmentation, strengthen the skin barrier, and calm redness, all simultaneously and in the same formula. It is well-tolerated at concentrations from 2% to 10%, works in both AM and PM routines, and is compatible with almost every other active ingredient.
Niacinamide is the active form of Vitamin B3, a water-soluble vitamin that your skin uses as a precursor to two critical coenzymes: NAD+ and NADP+. These coenzymes are involved in cellular energy production, DNA repair, and the synthesis of fatty acids that form the skin barrier. When you apply niacinamide topically, you are essentially providing your skin cells with the raw material to perform these functions more effectively.
It should not be confused with niacin (nicotinic acid), which is another form of Vitamin B3 that causes facial flushing when taken orally. Niacinamide does not cause this reaction.
This is niacinamide's most popular benefit, and it is well-supported. A double-blind study published in the British Journal of Dermatology found that 2% niacinamide significantly reduced pore size after 12 weeks of use. The mechanism: niacinamide reduces sebum production, which reduces the stretching of pore openings that makes them appear enlarged. Pores do not technically "shrink" — they have no muscles to contract — but by reducing the sebum pushing them open, niacinamide makes them appear measurably smaller.
Niacinamide regulates sebocyte activity — the skin cells responsible for producing oil. A study in the Journal of Cosmetic and Laser Therapy found 2% niacinamide reduced sebum production comparably to 4% clindamycin gel (a prescription antibiotic). For oily and combination skin types, this makes niacinamide one of the most effective non-prescription oil-control ingredients available.
Niacinamide inhibits the transfer of melanosomes — the packets that carry melanin pigment — from melanocyte cells to keratinocyte cells. This process is what causes dark spots to form and persist. A 5% niacinamide concentration has been shown in multiple studies to significantly reduce hyperpigmentation and improve skin evenness over eight weeks, performing comparably to 4% hydroquinone in some trials.
Niacinamide stimulates the production of ceramides, cholesterol, and free fatty acids — the three components of the lipid matrix that forms the skin barrier. A weakened barrier lets water escape (causing dehydration) and lets irritants in (causing sensitivity). Regular niacinamide use measurably increases barrier lipid levels, improving moisture retention and reducing reactivity over time.
The barrier-strengthening effect has a downstream consequence: when your barrier is stronger, irritants cannot penetrate as easily, which reduces the inflammatory response. Additionally, niacinamide has direct anti-inflammatory properties, suppressing the production of pro-inflammatory cytokines. This makes it particularly valuable for rosacea-prone and reactive skin.
A 5% niacinamide study published in the Journal of Cosmetic Dermatology found significant reductions in fine lines, wrinkles, and skin sallowness (yellowing) after 12 weeks. The mechanism is likely a combination of barrier strengthening (hydrated skin looks plumper), protein synthesis stimulation, and antioxidant effects that protect skin cells from oxidative damage.
The research shows clear results at 2% to 5% for most benefits. The 10% concentration popularised by The Ordinary is effective but not necessarily more so than 5% for most people — and some individuals with sensitive skin find 10% causes mild redness or flushing, which is more likely at higher concentrations. This is not a true "niacin flush" but a concentration-related mild irritation.
If you are new to niacinamide, starting at 5% and working up is a sensible approach.
Niacinamide is one of the most flexible actives in terms of formulation — it works in serums, moisturisers, toners, and even sunscreens. Its water-soluble nature means it belongs in the early, thinner layers of your routine.
In an AM routine: After cleansing and toning, apply your niacinamide serum before heavier moisturisers and SPF. It works synergistically with SPF as an antioxidant and anti-pollution defence.
In a PM routine: Apply niacinamide after cleansing. It is compatible with retinol (apply before retinol), AHAs (apply after acids have dried), and can be layered under or combined with hyaluronic acid without issue.
You can use niacinamide morning and night without issue — it has no photosensitivity risk and does not need to be restricted to one session.
There is a persistent myth that niacinamide and Vitamin C cannot be used together because they react to form niacin, causing flushing. This was a real concern with older, less stable formulations. In modern skincare products, the concentrations of both ingredients are too low for this reaction to occur at any meaningful level.
However, niacinamide can slightly reduce the potency of L-Ascorbic Acid Vitamin C by chelating with metal ions needed for its activity. If you are using a high-potency Vitamin C serum (15–20% L-Ascorbic Acid), it is worth applying it separately — Vitamin C in AM, niacinamide in PM — for maximum efficacy. At moderate concentrations, layering them is fine. Read our full guide on using niacinamide and Vitamin C together.
Almost everyone. It is particularly valuable for:
Niacinamide is the closest thing skincare has to a universal active. Its multi-pathway mechanism means it addresses several concerns simultaneously — pores, oil, pigmentation, barrier, redness — without the irritation that typically accompanies potent actives. At 5%, used twice daily, it is one of the highest-value additions to any routine regardless of skin type. Start there, give it 8–12 weeks, and the results will be measurable.
Build your niacinamide routine: Use Skin Stacker's routine builder to see how it fits with your other actives.