Niacinamide serum: what it does and what percentage to take

Niacinamide (vitamin B3) is the safest "working" ingredient in Korean skincare: every skin type, pregnancy included, and it mixes with almost everything.

What it does (with evidence)

• Less oil: studies show sebum dropping at 2–4% within weeks; the first pick for oily skin.
• Pores look smaller: less oil, less swelling of the pore; they do not actually shrink.
• Lightens marks: slows pigment reaching the surface; visible by week eight.
• Stronger barrier, less redness: boosts ceramide production, a separate win for sensitive skin.

What percentage

• 2–5%: the proven range. Enough for sensitive skin and for starting out.
• 10%: the most common; most people tolerate it well.
• 15–22%: marketing numbers. More percent is not more result; some people get redness and itching (niacin flush). If 10% does nothing, raising it will not help; a different ingredient will.

When, and with what

Morning or night, both is fine. After toner, before moisturiser.

• Goes with: vitamin C (no problem in modern formulas), retinol (eases the sting), AHA/BHA, hyaluronic acid, TXA, azelaic acid.
• Watch out: three or four products in one routine all carrying niacinamide push the total past 30%. If the toner, serum and cream all have it, keep it in one.

Picks

• Starting out, any skin: Jumiso Niacinamide 10 Serum 40ml, SKIN1004 Niacinamide 10 Boosting Shot Ampoule 30ml
• Oily / pores: COSRX The Niacinamide 15 Serum 20ml, Anua Peach 70 Niacin Serum 30ml NEW
• Cream form for marks: Round Lab Vita Niacinamide Dark Spot Cream 50ml
• Used to it, higher percentage: Nineless B-Boost 22% Niacinamide Serum 30ml

What will not happen

Skin will not turn "fair"; acne will not clear (that needs BHA alongside); deep marks will not vanish. What will: less oil, even tone, less redness.

Niacinamide is the best "first serum". The next one depends on your concern: acne, marks, pores and oil.

Sources

• Published clinical studies: sebum reduction at 2% niacinamide, less hyperpigmentation and redness at 4–5%, over 8–12 weeks.
• Evidence of extra benefit above 5% is weak; reports of irritation rise.