Niacinamide is the least exciting ingredient on the shelf and the one I recommend most often. It does several useful things at once, it suits almost every skin, and it is the rare active that does not require you to earn tolerance first.
What it does
- Reduces sebum — one of the few ingredients with a measurable effect on oiliness.
- Strengthens the barrier by supporting ceramide production, so skin holds water better.
- Calms redness, which is why it suits reactive and rosacea-prone skin.
- Fades pigment by interrupting the transfer of melanin to surface cells — a different mechanism from vitamin C, which is why the two work well together.
- Makes pores look smaller by keeping them clear and the skin around them firm.
No single one of these is dramatic. Together, over a few months, they are the reason skin starts looking calmer and more even without anything obvious having changed.
The strength that matters
Five per cent is where the evidence sits. Ten per cent is fine for oily skin that tolerates it. Twenty per cent is marketing — above about ten, the extra brings irritation rather than benefit, and the flushing people blame on “niacinamide sensitivity” is almost always a too-high percentage.
If 5% stings, the problem is usually the rest of the formula rather than the niacinamide itself.
How to use it
- Morning or evening — it is stable and not sun-sensitising, so either works.
- After cleansing, before moisturiser.
- Daily from the start. Unlike retinoids, it does not need a build-up period.
- Give it eight weeks for oil and pores, twelve for pigment.
The myth about vitamin C
You will read that niacinamide and vitamin C cancel each other out. That comes from 1960s research using raw ingredients at high heat, and it does not describe what happens in a modern formula on a face. Using them together is fine. If you would rather not, put vitamin C in the morning and niacinamide at night and the question disappears.
It also layers happily with retinoids and acids, and it reduces the irritation both of those cause. If you are starting a retinoid, niacinamide alongside it makes the first six weeks noticeably easier.