Niacinamide

Niacinamide is the amide form of vitamin B3. It is water-soluble, stable across a wide pH range, and among the most studied topical actives in dermatology[1].

What it does

In the skin it is a precursor to NAD⁺ and NADP⁺, coenzymes that sit upstream of energy metabolism and lipid synthesis. Practically, that shows up as three well-replicated effects: more ceramides and a tighter barrier, less melanosome transfer to keratinocytes (so a more even tone)[2], and a modest reduction in sebum output[3].

The evidence

A 12-week, double-blind, split-face trial of 5 % niacinamide found significant improvements in fine lines, hyperpigmented spots, red blotchiness and yellowing versus vehicle[1]. Against inflammatory acne, 4 % nicotinamide gel performed comparably to 1 % clindamycin over eight weeks[4]. In rosacea-prone skin, a niacinamide moisturiser improved barrier function and reduced redness[5].

How to use it

Two to five per cent is where the trials sit. It plays well with almost everything, including retinolRetinolStrongRetinol · Vitamin A alcoholThe best-evidenced over-the-counter retinoid for photoageing; now capped at 0.3 % in EU leave-on products.Open in the Index → and azelaic acidAzelaic acidStrongAzelaic Acid · Dicarboxylic acidPrescription-grade evidence for rosacea and acne at 15–20 %; cosmetic versions run lower.Open in the Index →. The long-running worry about combining it with ascorbic acidAscorbic acidStrongAscorbic Acid · Vitamin C (L-ascorbic acid)The active form of vitamin C; well-evidenced for photoageing at 10–20 % and low pH, but unstable.Open in the Index → traces back to conditions (heat, hours, high concentrations) that don't apply to a serum on your face.