The Ultimate Guide to COSRX Serums
Looking for a simple, effective way to upgrade your routine this season? These three COSRX serums cover the essentials: oil balance, glow, and deep hydration. Below you’ll find who each one is for, what results to expect, and how to layer them for maximum payoff.
COSRX The Niacinamide 15 Serum
Best for: Oily / combination / breakout-prone skin, visible pores, uneven texture.
Why you’ll love it
- Helps balance excess oil and improve the look of enlarged pores.
- Supports a clearer-looking complexion with a smoother skin feel.
- Lightweight texture that layers easily under moisturiser and SPF.
Key highlights
- Concentrated niacinamide to help refine tone and texture.
- Soothing + barrier-supporting components for daily use.
- Fragrance-free, suitable for AM & PM.
How to use
- After cleansing and toner, apply 2–3 drops to face and neck.
- Pat until absorbed, then follow with moisturiser.
- AM: finish with broad-spectrum SPF 50.
Pro tip: Pair with Hyaluronic Acid 3 for extra hydration if you also feel tightness or dryness.
COSRX The Vitamin C 23 Serum
Best for: Dull tone, uneven pigmentation look, early fine lines, lack of radiance.
Why you’ll love it
- Helps visibly brighten and promote a more even-looking complexion.
- Antioxidant care to support the look of smoother, more radiant skin.
- Fast-absorbing formula that works well under sunscreen and makeup.
Key highlights
- High-strength vitamin C (ascorbic acid) at 23%.
- Comforting, hydrating base to minimise the feel of sting for daily use.
- Best used in the morning with SPF (or at night if preferred).
How to use
- Apply 2–3 drops on clean, dry skin after toner/essence.
- Allow 30–60 seconds before moving to the next step.
- Layer moisturiser; in AM always finish with SPF 50.
Note: If you’re new to strong actives, start 3–4 times/week and build up. Avoid using on the same night as high-strength exfoliating acids or retinoids.
COSRX The Hyaluronic Acid 3 Serum
Best for: Dehydrated, tight, or rough skin; fine dehydration lines; all skin types (including sensitive).
Why you’ll love it
- Delivers multi-level hydration for a plumper, smoother look.
- Helps strengthen the feel of the skin barrier and reduce tightness.
- Feather-light slip that layers with any routine, AM or PM.
Key highlights
- Multiple molecular weights of hyaluronic acid for surface + deeper hydration feel.
- Comforting humectants and soothing components for daily comfort.
- Fragrance-free; ideal as your “hydration booster” step.
How to use
- Apply 2–3 drops on slightly damp skin after toner/essence.
- Seal with moisturiser to lock in hydration.
- Use AM & PM; finish with SPF in the morning.
How to choose (quick guide)
- Shine/pores/breakouts? Start with Niacinamide 15.
- Dull or uneven tone? Go for Vitamin C 23.
- Dry/tight skin or makeup pilling? Add Hyaluronic Acid 3.
Layering made easy
- AM: Cleanser → Toner → Vitamin C 23 → Hyaluronic Acid 3 → Moisturiser → SPF 50.
- PM (option A): Cleanser → Toner → Niacinamide 15 → Hyaluronic Acid 3 → Moisturiser.
- PM (option B with retinoid): Cleanser → Toner → Retinoid night → Hyaluronic Acid 3 → Moisturiser. (Use Niacinamide 15 on alternate nights.)
Patch test: Apply a small amount behind the ear or on the jawline for 24 hours before first full use.
FAQ
Can I use Niacinamide 15 and Vitamin C 23 together?
Yes—many routines alternate or separate them by time of day (Vitamin C in the morning, Niacinamide at night). If your skin is new to actives, introduce one product at a time.
Which serum should I start with?
Start with your main concern: oil/pores → Niacinamide; dullness → Vitamin C; dehydration → Hyaluronic Acid. You can combine two serums once your skin is comfortable.
Is Vitamin C 23 suitable for sensitive skin?
High-strength vitamin C can feel active. Start 3–4 times per week, apply to dry skin, and always use SPF in the morning.
Build your routine
Ready for clearer, brighter, hydrated skin? Explore the trio below and create a routine that fits your goals.