Niacinamide: what it really does and how to choose it (2%, 5%, 10%)

Niacinamide is everywhere: in serums, creams, toners and sunscreens. It is one of the few cosmetic actives whose mechanisms are genuinely documented in humans, and one of the best tolerated. But the difference between a 2% serum and a 10% or 20% formula is not what the marketing suggests. Here is what niacinamide does, what it does not do, and how to choose the right concentration for your skin.

What is niacinamide?

Niacinamide, also called nicotinamide, is a form of vitamin B3. It is water-soluble, stable in light and heat, and fits into almost any texture with no pH constraints. That explains why it is so common in Korean skincare: it is easy to formulate, inexpensive and compatible with nearly every other active.

In the skin it acts as a precursor to coenzymes (NAD+, NADP+) involved in cellular energy and repair. This "fuel" role explains the range of its effects: it does not act on a single target but on several functions of the epidermis at once.

What niacinamide does: the four documented effects

1. Regulating sebum and visibly tightening pores

Several studies have measured a drop in sebum production after a few weeks of use. Less sebum means a pore that is less stretched and skin that is less shiny by the end of the day. Pores do not "close", but they look finer because they are less congested.

2. Fading dark spots and evening out skin tone

Niacinamide slows the transfer of melanosomes (the pigment "packages") from melanocytes to surface cells. It does not block melanin production; it slows its distribution. That makes it useful for post-acne marks and uneven tone, especially combined with sunscreen, without which no result on dark spots lasts.

3. Strengthening the skin barrier

It stimulates the synthesis of ceramides and other barrier lipids, which reduces water loss. Skin that holds water better is skin that reddens less, tolerates strong actives more easily and stays hydrated for longer. It is the least spectacular effect, but the most useful day to day.

4. Calming inflammation

Its anti-inflammatory action is documented on acne and redness. It does not replace a dermatological treatment, but it makes the skin less reactive, which is why it appears in so many formulas for blemish-prone skin.

2%, 5%, 10%: which niacinamide serum concentration to choose?

This is where marketing muddies the water. The available literature puts niacinamide's effectiveness at 4 to 5% for sebum and dark spots, and from 2% for barrier support. Above 5%, no additional benefit has been convincingly demonstrated, while the risk of transient flushing and tingling increases. Formulas at 10, 15 or 20% are therefore mostly a label arms race.

• 2%: the support dose. Ideal in a cream, toner or multi-active serum, for the barrier and a mild glow. That is the dose in Beauty of Joseon's Glow Serum, which pairs 2% niacinamide with propolis extract: a radiance and comfort serum rather than a dark-spot treatment.
• 4 to 5%: the active dose. This is the concentration to aim for on sebum, pores and post-acne marks. The AXIS-Y Dark Spot Correcting Glow Serum is formulated at 5%, with squalane for hydration: the right entry point for uneven skin tone.
• 10% and above: the label dose. Reserved for very tolerant oily skin that has already tried 5% without any reaction. For most skin types it means more risk of discomfort for the same result.

Another option: niacinamide in a cream rather than a serum. The Medicube TXA Niacinamide Capsule Cream combines it with tranexamic acid, another tone-evening active, in a capsule-and-gel texture you mix yourself. A way to get the effect on skin tone without adding a step.

How to fit niacinamide into a Korean skincare routine

Niacinamide is applied morning and evening, after cleansing and toning, before your moisturiser. It layers without issue over centella, hyaluronic acid, ceramides and peptides. In the morning, always finish with sunscreen: that is the condition for any effect on dark spots to become visible.

Two useful clarifications:

• Niacinamide and vitamin C do not cancel each other out. That myth comes from old laboratory experiments run at high temperature with niacin, not niacinamide. In normal cosmetic use the two combine very well; you can use a vitamin C serum in the morning and niacinamide in the evening, or both together.
• Niacinamide and exfoliating acids: avoid applying them in the same layer. A very low pH (that of a concentrated AHA or BHA) can convert part of the niacinamide into niacin, which causes redness. Wait a few minutes between them, or keep the exfoliant for other evenings.

Which skin types, and how long does it take?

Niacinamide suits almost every skin type: combination and oily for sebum and pores, dull or marked skin for tone, sensitive skin for the barrier. The only people who should test carefully are those who redden at the slightest application; in that case start with a 2% product in a cream, two evenings a week.

The first effects on shine appear within two to four weeks. On dark spots and skin texture, allow eight to twelve weeks of regular use. A serum used for ten days and then abandoned will do nothing: consistency produces the result, not concentration.

Browse our full niacinamide collection, and our products for dark spots and dull skin if evening out your tone is your priority.

FAQ: niacinamide

Is niacinamide a day or night serum?

Both. It is light-stable and does not cause photosensitivity. In the morning it complements sunscreen; in the evening it supports barrier repair. One application a day is enough if you prefer a short routine.

Can you use niacinamide with retinol?

Yes, and it is actually a good pairing: niacinamide reduces the dryness and redness typical of the first weeks of retinol. Apply it before, or mixed into, your night cream.

Why does my skin flush with a 10% serum?

That is the niacin flush, a transient reaction linked to high concentrations or partial conversion into niacin. It is not an allergy, but it is a sign the dose is too strong for your skin: switch to a product at 5% or less.

Does niacinamide make pores disappear?

No. Pore size is largely genetic. Niacinamide makes them less visible by reducing the sebum that stretches them, but no cosmetic removes them.