Niacinamide: what it genuinely does, and why 10 per cent is not twice as good as 5

Niacinamide is a form of vitamin B3 and one of the most reliably useful ingredients in modern skin care. It is also the ingredient most damaged by marketing arithmetic, where 10 per cent is sold as better than 5 and 20 per cent as better still.

What it is reasonably supported for

• Barrier support - it contributes to ceramide production, which is why it helps skin that stings and flakes.
• Redness and visible inflammation, where dermatology consensus work has repeatedly landed in its favour.
• Dark spots and post-inflammatory hyperpigmentation - it interferes with pigment transfer to skin cells, so it fades marks rather than bleaching skin.
• Sebum and the look of pores - modest, real, and slower than the before-and-after photographs suggest.
• Fine lines, at the gentler end - a supporting act rather than a retinoid replacement.

What it will not do is resurface skin, clear cystic acne or replace sunscreen. It is a maintenance ingredient: unglamorous, cumulative, and most valuable when it sits in a routine for months.

The percentage question, settled

Most of the clinical work sits in the 2 to 5 per cent range. Formulas at that level are effective and very well tolerated. Above roughly 10 per cent, the frequently reported outcome is not more benefit but more flushing, stinging and irritation - particularly on skin that is already compromised.

If a niacinamide serum makes you flush, the usual fix is a lower percentage or a version inside a moisturiser, not pushing through. Skin that is stinging is not adapting - it is telling you the formula is wrong for it.

The vitamin C myth

The claim that niacinamide and vitamin C cancel each other out traces back to old work on unstable high-heat conditions that bear no resemblance to a serum on a face. Peer-reviewed dermatology since has found no efficacy loss when the two are layered or formulated together.

The same applies to the retinol pairing rumour. There is no credible evidence that niacinamide blunts a retinoid, and reasonable evidence that it helps skin tolerate one by supporting the barrier. If a combination irritates you, that is a formulation or frequency issue, not chemistry cancelling out.

How to fit it in

• Morning or night; it is not photosensitising, so either works.
• After cleansing, before heavier creams. If your moisturiser already contains it, a separate serum is usually redundant.
• Start at every other day if your skin is reactive, then daily.
• Give it eight to twelve weeks before judging pigmentation effects. Redness often improves faster.
• One niacinamide product in a routine is enough. Stacking a toner, a serum and a moisturiser that all contain it is how people end up irritated while blaming the wrong bottle.

What to look for when buying

Check where niacinamide sits in the ingredients list - a formula claiming 5 per cent should not have it below the preservatives. Check the rest of the formula for things your skin dislikes: high alcohol content, strong fragrance, or a cocktail of four other actives that makes it impossible to tell what caused a reaction.

And check the price honestly. Niacinamide is inexpensive as a raw material, formulations are well understood, and there is very little reason for a basic serum to cost what a prestige brand charges for one.