COSRX THE NIACINAMIDE 15 SERUM 20ML

100% Genuine (Adilsons policy) · Fragrance-Free (confirmed in the declared INCI) · FA-Safe (no Malassezia-feeding esters detected) · Halal-Friendly* / Vegan-Friendly*.

PIH vs PIE: this serum targets PIH — brown/tan flat marks from excess melanin — via niacinamide's melanosome-transfer-inhibition mechanism. It does not address PIE (red/pink marks from damaged capillaries); that needs centella or azelaic acid instead.

Pros: a genuinely high, clinically-relevant niacinamide dose, fragrance-free, includes Zinc PCA for sebum support and Acetyl Glucosamine for mild texture refinement. Caveats: at 15%, a minority of reactive skin experiences flushing — this is not the gentlest niacinamide option, and it has no SPF of its own.

Mauritius humidity makes surface oil feel like dirt, tempting over-washing that strips the acid mantle and triggers compensatory sebum overproduction. Niacinamide at this dose genuinely helps regulate sebum production over weeks of consistent use, which is a more durable fix than repeated harsh cleansing.

Bedside-compatible: yes. No rinsing, precise dosage is just a few drops, no complex technique. On a low-energy day, this serum plus a moisturizer is a legitimate minimal routine that still moves the needle on pigmentation and pore concerns.

Step 1 (When): AM and/or PM. Step 2 (How much): 2-3 drops or roughly 1 pump. Step 3 (How): Press into slightly damp or dry skin; wait 30-60 seconds before the next step.

Introduce this as the ONLY new product in your routine. Wait a full 14 days before adding anything else. This isolation window ensures you can identify whether any reaction is caused by this specific product, since 15% is high enough to cause flushing in a minority of users.

1. Gentle cleanser (optional) → 2. Toner (optional) → 3. COSRX The Niacinamide 15 Serum → 4. Moisturizer → 5. Sunscreen SPF50+ PA++++ (mandatory). Pigmentation routines fail without daily SPF — unprotected UV exposure regenerates the same melanin niacinamide is working to regulate.

1. Double cleanse → 2. Toner (optional) → 3. COSRX The Niacinamide 15 Serum → 4. Moisturizer. At 15%, this does not occupy the strict "active lane" the way a retinoid or strong acid does, but very sensitive or reactive skin should still avoid pairing it same-night with a high-dose Vitamin C or strong exfoliant until tolerance is confirmed.

Technique: Press, don't rub. Required skin state: damp or dry. Wait time: 30-60 seconds before the next step.

This is an encyclopedia map of all product types. You do not use all of these daily. You select modules based on your skin state.

Global rules: viscosity ladder thinnest → thickest, water-phase before oil-phase, treatments before seals. Wait-time defaults: watery layers 10-20s, serums 30-60s, before sunscreen 10-15 min. Amount defaults: serum 2-3 drops or 1 pump, gel moisturizer 1-1.5 peas, sunscreen 2-finger rule. If the routine pills, stings, or feels heavy — reduce layers, never increase.

AM Maximum Stack: 1. Rinse/gentle cleanse (optional) 2. Toner (optional) 3. Pigment support lane — this product's slot 4. Hydration serum lane (optional) 5. Eye cream (optional) 6. Moisturizer 7. Sunscreen SPF50+ PA++++ (non-negotiable). PM Maximum Stack: 1. Double cleanse 2. Toner (optional) 3. Anchor active — this product's slot 4. Moisturizer 5. Sleeping mask (optional). Do not layer retinoids with AHA/BHA in the same night; keep "one lane" per night.

One-lane rule: Retinoid OR Exfoliation OR Strong Vitamin C (LAA) OR Acne-control active per routine; this serum's pigment-support lane can generally accompany any of them once tolerance is confirmed, but introduce cautiously if you're also running a strong Vitamin C serum.

Water-thin-to-light-fluid serum. Apply after toner, before moisturizer and sunscreen.

Before starting, your routine should already include a gentle cleanser and daily sunscreen — this serum's brightening effect depends entirely on consistent SPF use.

Dark spots (PIH): 15% Niacinamide inhibits melanosome transfer from melanocytes to keratinocytes, fading brown/tan flat marks over time. Enlarged pores/texture: Acetyl Glucosamine (2%) provides mild exfoliative smoothing. Excess sebum: Zinc PCA (1%) supports sebum regulation, treating acne-adjacent breakouts as a secondary benefit, not a primary acne treatment.

This product cannot fade PIE (red/pink marks), cannot replace a dedicated acne-treatment active for active inflammatory acne, and cannot replace sunscreen.

Sealing moisturizer: primary — COSRX Advanced Snail 92 All In One Cream 100g; alternatives — Beauty of Joseon Dynasty Cream 50ml, SKIN1004 Madagascar Centella Probio-Cica Enrich Cream 50ml, Anua Birch Moisture Boosting Cream 50ml.

Sunscreen (mandatory, since results depend on it): primary — SKIN1004 Madagascar Centella Hyalu-Cica Water-Fit Sun Serum 50ml; alternatives — Beauty of Joseon Relief Sun: Rice + Probiotics 50ml, Anua Heartleaf Silky Moisture Sun Cream 50ml, SKIN1004 Madagascar Centella Air-Fit Suncream Light 50ml.

MYTH: "More niacinamide always means faster brightening." REALITY: 15% is already a strong dose — going higher doesn't necessarily improve results and increases flushing risk in reactive skin; consistency and daily SPF matter more than concentration alone past this point.

MYTH: "Niacinamide bleaches skin." REALITY: it regulates melanin production to fade excess pigment toward your natural tone — it cannot lighten your natural complexion.

Chronic stress elevates cortisol, which increases inflammatory pigment response and sebum production. Niacinamide's barrier-support and sebum-regulation roles help buffer some of that stress-driven skin behavior, though it does not address the stress itself.

Permeability: Water-Permeable (wudu-compatible). This watery serum absorbs within a minute and leaves no continuous film once fully dry.

Adilsons provides this assessment based on the product's physical properties. Rulings on wudu validity vary between scholars. Consult your own trusted Islamic authority.

Mauritius tap water hardness varies by region; a pH-balancing toner before this serum helps counteract any tight, filmy feeling hard water leaves after cleansing.

Full INCI: Water, Pentylene Glycol, Niacinamide, Butylene Glycol, Acetyl Glucosamine, 1,2-Hexanediol, Zinc PCA, [--- Estimated 1% Line ---] Trehalose, Xanthan Gum, Pullulan, Allantoin, Ethylhexylglycerin, Sodium Phytate, Citric Acid, Tocopherol.

Preservative system: 1,2-Hexanediol and Ethylhexylglycerin (glycol-based preservative boosters); Sodium Phytate and Citric Acid act as chelating/pH-adjusting agents.

Fragrance status: Fragrance-Free. Scent: effectively none. EU 26 allergen screen: none detected. Alcohol: Alcohol-Free.

Halal: *Self-assessed by Adilsons based on available INCI data. No ethanol from fermentation and no animal-derived ingredients detected. This is NOT a formal Halal certification.

Vegan: *Self-assessed by Adilsons based on available INCI data. No animal-derived ingredients detected. This is NOT a formal vegan certification.

Cruelty-free: *Brand-stated policy, not independently certified by PETA or Leaping Bunny. COSRX sells through mainland Chinese retail channels, where post-market animal testing may be legally required; cross-border e-commerce sales may be exempt.

Microplastic-Free: Yes.

MFDS classification: Not confirmed as a registered Functional Cosmetic for this exact SKU, though niacinamide is a recognized whitening-functional ingredient category in Korea at appropriate doses. Whitening translation: the Korean "미백" (mibaek) classification means regulating melanin production to fade dark spots toward your natural tone — it does not bleach or change your natural complexion.

Clinical claim: *Brand-published marketing material cites a 19% improvement in pigmentation and a 15% reduction in blemishes after four weeks. This is a brand-stated figure — the study institution, sample size, methodology, and whether it was independently peer-reviewed were not found in this research pass, so treat it as a marketing claim rather than independently verified clinical evidence. Evidence confidence: High for niacinamide's brightening/sebum-regulation mechanism generally; Low-Medium for the specific 19%/15% figures pending independent verification.

Fungal Acne Safety: FA-Safe. No Malassezia-feeding fatty acids or esters identified in this short INCI.

Assessment: Low. This water-thin serum absorbs cleanly; pilling risk mainly appears if layered under a heavy silicone-based sunscreen without a full absorption wait.

Fresh color is clear to very pale. A yellowed shift or off smell signals oxidation — discard rather than use. Store away from direct bathroom-window sun and shower steam.

Patch test on the inner forearm for 24 hours, then behind the ear for 24 hours, before first facial use — this matters more here than on a lower-dose niacinamide product because of the real flushing risk in reactive skin at 15%.

If adverse reaction: STOP ALL ACTIVES. For 72 hours, use ONLY a gentle cleanser, plain moisturizer, and mineral SPF. After 72 hours, reintroduce ONE product per 14 days. Seek emergency care for hives, swelling, blistering, persistent burning, or breathing difficulty.

1. Starting at 15% without ever having tried a lower-dose niacinamide product. 2. Skipping sunscreen and expecting the pigmentation results to hold. 3. Stacking this with another high-dose niacinamide or brightening product hoping for faster results. 4. Assuming it treats red (PIE) marks the same as brown (PIH) marks. 5. Expecting acne-clearing results — it supports sebum regulation, not primary acne treatment.

At 2-3 drops per use, twice daily, a 20ml bottle lasts roughly 5-7 weeks for an average face. Reorder about 1-2 weeks before it visibly runs low.

AM: Cleanse (optional) → toner (optional) → this serum → moisturizer → sunscreen (mandatory). PM: Double cleanse → toner (optional) → this serum → moisturizer.

If your primary goal is fading dark spots: pair this serum with strict daily SPF — niacinamide cannot outpace ongoing UV-driven pigment production. If you're new to niacinamide entirely: consider trialing a lower-concentration product first before committing to this 15% strength.

Stock-true bundle — Brighten & Seal: this serum + COSRX Advanced Snail 92 All In One Cream 100g. How to use: serum first on damp skin, cream sealed on top, AM and PM. Why included: the cream's barrier support buffers any mild flushing while the serum does its brightening work.

After purchasing, you will receive our skincare education email series covering this product in depth.

The recommendations above are based on formulation synergy with The Niacinamide 15 Serum, not on margin or stock levels. If a pairing does not exist in our catalog, we say so. If you already own a product that fills the same role, use what you have first.

If you want a lower-concentration niacinamide product to start with, or one paired with tranexamic acid for stronger PIH targeting, Anua Niacinamide 10%+TXA 4% Dark Spot Correcting Serum 30ml is a genuine in-catalog alternative.

Choose this COSRX serum for its higher raw niacinamide concentration (15% vs 10%) plus Zinc PCA and Acetyl Glucosamine for texture and sebum support; choose the Anua serum if you want tranexamic acid added specifically for stubborn PIH, or prefer starting at a slightly lower niacinamide dose.

If PIH is stubborn and you want TXA added specifically for it: the Anua serum is the stronger pick. If you've tolerated niacinamide before and want the highest reasonable single-active dose: this COSRX serum is the better fit.

If you match 2 or more upgrade triggers above, the alternative is worth choosing. If not, this serum is sufficient. Consistency beats complexity.

This product's PRIMARY function is high-dose niacinamide brightening and sebum support. You do not need this if you already own an unfinished niacinamide serum in a similar dose range — finish it first. Stacking assessment: No Benefit if paired with another high-dose niacinamide serum (redundant, and increases flushing risk); Significant Benefit if paired with a different-pathway active (retinoid, exfoliant) on alternating nights.

This product is sourced through authorized Korean distributors — primarily Craver Co., Ltd (South Korea), alongside other verified distribution partners. Craver is a major Korean beauty distributor and the parent company of SKIN1004, handling authorized distribution for multiple K-beauty brands. All products are shipped directly to Mauritius via verified channels.

For comprehensive information about how we verify authenticity, our layered verification system, and how to check your product at home, visit our dedicated Authenticity and Trust page.

Quick checks for this SKU: the bottle carries a laser-etched batch code on the base, and COSRX's official QR verification tool at official.cosrx.com/record can confirm current-generation stock.

COSRX built its early reputation on a minimal, low-pH, "skin-friendly" formulation ethos before its 2023 acquisition by Amorepacific. This serum represents the brand's higher-concentration, single-active-forward product family aimed at customers who want a specific, measurable active dose rather than a blended multi-ingredient formula.

Third-party retail listings (Soko Glam, What's In My Jar) describe this as a strong, no-frills niacinamide option, formulated without fragrance, parabens, sulfates, artificial colors, or mineral oil. No aggregate numeric rating specific to this exact SKU, and no dedicated Reddit thread, was found in this research pass.

Common praise: effective for fading dark spots and refining texture at a meaningfully high concentration. Common complaint: not clearly identified in the sources checked this pass — worth a fresh check on a future research cycle, especially given the real flushing risk at 15% that some niacinamide-sensitive users report in general.

Sustainability: check the base for a recycling code; not refillable.

Is 15% niacinamide safe? Generally yes for most skin, but it's a genuinely high dose — patch test first, especially if you've never used niacinamide before.

Will it fade red acne marks? No — that's PIE, which needs centella or azelaic acid, not niacinamide.

Can I use it with Vitamin C? Generally compatible in modern formulas, though sensitive skin may want to split AM/PM or wait 10-15 minutes between the two.

Is the 19%/15% clinical claim verified? It's a brand-published figure; the study details were not independently found in this research pass, so treat it as a marketing claim rather than fully verified clinical evidence.

Is it vegan? Self-assessed yes based on the declared INCI.

Niacinamide

Vitamin B3 derivative that inhibits melanosome transfer, supports barrier function, and helps regulate sebum.

PIH

Post-inflammatory hyperpigmentation — brown/tan flat marks from excess melanin.

PIE

Post-inflammatory erythema — red/pink marks from damaged capillaries; not treated by niacinamide.

Zinc PCA

A zinc salt associated with sebum regulation and mild anti-acne support.

Acetyl Glucosamine

A mild exfoliative amino-sugar derivative that supports texture refinement, often used alongside niacinamide for pigmentation.

Every product sold by Adilsons Beauty is 100% genuine, sourced through authorized Korean distribution channels. Full details on our verification system: Authenticity and Trust.

Our team is available to help you build a routine, troubleshoot reactions, and answer ingredient questions. WhatsApp: +230 5 778 2336.

For in-depth skincare education, visit our blog at adilsons.mu/blogs/k-beauty or subscribe to our email to get our guided education series delivered to your inbox.

Coverage: Island-wide delivery (Mauritius).

Processing and Timing: Orders process in 1-2 business days; usually ready by Day 3 for pickup by our delivery partners/regional team. Partner collection can take up to 1 week. After pickup, delivery typically takes 1-5 business days (weekdays only).

Express: May be available by region; request on WhatsApp: +230 5 778 2336.

Liquids/Sensitive Items: Serums, toners, liquid makeup (and kits containing liquids) are pickup or door-to-door only; checkout enforces this.

Scheduling: Deliveries run by region on set schedules; we will contact you the evening before.

Pickup: Citadelle Mall pickup available.

Returns: No change-of-mind exchanges.

Refunds (Summary): For defective/damaged on receipt (report within 48h), wrong item, or manufacturing defect within 6 months. Refunds via bank transfer (7-10 business days); card refunds may incur a 5% processor fee (fee not charged for defects/order errors). Opened skincare/personal-care items are non-returnable (except if damaged on delivery).

Source of Truth: This is a quick snapshot. If anything differs, the policy pages are final.

Store Policies: For the most up-to-date information, please review our Shipping Policy and Refund Policy.

Best for: anyone with PIH, enlarged pores, or excess sebum who has already tolerated niacinamide at a lower dose and wants a stronger, single-active-forward serum.

Key benefits: a genuinely high 15% niacinamide dose plus Zinc PCA and Acetyl Glucosamine, fragrance-free, fast-absorbing texture.

Keep in mind: a minority of reactive skin experiences flushing at this concentration, it carries no SPF of its own, and the brand's specific 19%/15% clinical figures are not independently verified.