cosrx The Niacinamide 15 Serum 20ml

Fifteen percent Niacinamide in a 20 ml bottle — a concentration few serums state this openly. Cosrx isn't banking on the packaging; it's banking on what happens after the first few weeks of use. A size that lets you try it before committing, or tuck into a wash bag without giving anything up.

Texture and ingredients — Niacinamide is dosed at 15%, a clinically active level for evening out skin tone and regulating sebum. Acetyl Glucosamine, a glucosamine derivative, works alongside Niacinamide to refine skin texture. Zinc PCA helps balance oily areas without drying the skin out. Trehalose, a natural sugar with strong moisture-binding properties, holds water in the upper layers of the skin. Allantoin and Tocopherol round out the formula to soothe and protect the skin barrier. The texture is lightweight and absorbs within seconds — no sticky or greasy residue.

How to use it — After cleansing, at the serum step, place a few drops into the palm of your hand. Apply from the centre of the face outward toward the temples, massaging gently with your fingertips until fully absorbed. Unlike the common assumption about concentrated serums, this one works morning and evening. In the morning, it layers under a sunscreen of at least SPF 30 — a step the brand explicitly highlights, and one that keeps the formula working as intended. At night, it primes the skin for the products that follow.

• Niacinamide at 15% — the concentration is clearly listed in the INCI ingredients list.
• Zinc PCA: balances sebum production without a drying effect.
• Acetyl Glucosamine works in synergy with Niacinamide to smooth skin texture.
• 20 ml size: ideal for testing tolerance to a high concentration before moving to a full-size bottle.
• If used in the morning, always apply SPF 30 or higher on top — an explicit recommendation from the brand.