The AHA 2 BHA 2 Blemish Treatment Serum

COSRX

The AHA 2 BHA 2 Blemish Treatment Serum

The AHA 2 BHA 2 Blemish Treatment Serum

COSRX

the-aha-2-bha-2-blemish-treatment-serum

Serum

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Morning or Evening?

Morning
Evening
Both

How often will you use this product?

Everyday
Every other day
Every 3 days
Every 4 days
Every 5 days
Every 6 days
Once a week
Twice a week
On specific days
As needed
On rotation

Notes

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Compatibility Score

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Highlights

WHAT IS IT?

Blemish treatment serum

FEATURES

Highly concentrated with 2% AHA and 2% BHA serum in a pure cotton ball, soothes acne-scarred skin, cares for blackheads and whiteheads.

BEST FOR

Acne-prone skin, skin with blackheads and whiteheads

CHECKS

Free of sulfates, parabens

Who Is It For?

Adults (18+) Both Men And Women

What Does It Help With?

Acne Scars Blackheads Whiteheads

Budget

Affordable

How To Use

Which routine should it be used in?

Morning
Evening
 
Cleanse
Tone
Eyecare
Serum
Moisturize
Suncare
 

Instructions:

Take out the cotton ball using the tongs included. Gently tap a cotton ball directly onto target areas.

Key Information

Vegan
Cruelty-free
Sensitive-safe
Non-comedogenic
Hypoallergenic
Microbiome-safe
Preservative-free
Eco-friendly
Pregnancy-safe
Oil-free

What COSRX Says

Product Description:

Highly concentrated with 2% AHA and 2% BHA, this serum in a pure cotton ball quickly and easily soothes acne-scarred skin and instantly cares for blackheads and whiteheads.

About the Brand:

COSRX has revolutionized Korean skincare with its minimalist, problem-solving approach. Known for high-concentration formulas and clean ingredient lists, this brand focuses on effective solutions for various skin concerns. Experience the perfect balance of science and simplicity with COSRX's targeted treatments that deliver visible results.

Ingredients Overview

Ingredients List

Water, Propanediol, Polysorbate 20, Glycolic Acid, Salicylic Acid, Gluconolactone, Zinc PCA, Allantoin, Sodium Hyaluronate, Sodium Hydroxide, Dipropylene Glycol, Hydroxyacetophenone, Caprylyl Glycol, Ethylhexylglycerin, Dipotassium Glycyrrhizate, 1,2-Hexanediol, Disodium EDTA

Key Ingredients

AHA 2%, BHA 2%

Ingredients Details

Allantoin

Common Name(s): 5-ureidohydantoin,glyoxyldiureide,aluminum dihydroxy allantoinate

CAS Number: 97-59-6

DESCRIPTION

What It Does: Soothes irritation, accelerates wound healing, promotes skin cell renewal, and provides mild keratolytic exfoliation.

Why It's Used: Gold standard multi-function soothing active โ€“ one of the most widely used cosmetic ingredients across all product types for its exceptional tolerability and clinically proven multi-action skin conditioning.

How It Works: Promotes keratinocyte proliferation and fibroblast migration for wound healing. mild keratolytic activity by disrupting corneocyte binding. anti-irritant via direct protein binding and anti-inflammatory cytokine reduction. humectant activity via hydroxyl groups.

Typically Found In: Post-procedure products,sensitive skin formulas,wound care,anti-acne treatments,baby products

TECHNICAL DETAILS

Primary Category: Active ingredient โ€“ soothing / anti-inflammatory

Secondary Functions: Wound healing,keratolytic,anti-irritant

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.1%โ€“2%

SOURCING & ETHICS

Vegan Status: Yes โ€“ synthetic or comfrey-derived

Halal Status: Yes

Source Notes: Plant-derived extract or synthetic.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 โ€“ very low

Comedogenicity Rating: 0/5 โ€“ non-comedogenic

Sensitivity Concerns: Exceptionally well-tolerated; suitable for all skin types including baby and compromised skin.

Safe for Sensitive Skin: Yes โ€“ particularly recommended for sensitive skin

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile. ewg score: 1.

Works Well With: Ceramides,panthenol,allantoin,hyaluronic acid,centella asiatica

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Allantoin's keratinocyte proliferation stimulation occurs via receptor-mediated signaling (possibly machr activation) rather than non-specific irritation-driven proliferation, making it a true wound-healing stimulant rather than a pro-inflammatory proliferative signal.

Last Verified: Cosing database,cir safety assessment,araรบjo et al. allantoin review

Primary Sources: 2026-03-12

Gluconolactone

Common Name(s): D-gluconolactone,delta-gluconolactone

CAS Number: 90-80-2

DESCRIPTION

What It Does: Provides the gentlest chemical exfoliation with simultaneous antioxidant, moisture retention, and barrier support.

Why It's Used: Preferred exfoliant for rosacea, eczema, sensitive skin, and post-procedure recovery where standard ahas cause unacceptable irritation.

How It Works: Hydrolyzes slowly on skin surface to gluconic acid providing gentle exfoliation. multiple hydroxyl groups enable water binding (humectant) and metal chelation (antioxidant).

Typically Found In: Sensitive skin exfoliants,rosacea treatments,eczema care,post-procedure recovery

TECHNICAL DETAILS

Primary Category: Active ingredient โ€“ polyhydroxy acid (pha)

Secondary Functions: Gentle exfoliation,antioxidant,humectant

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 5%โ€“15%

SOURCING & ETHICS

Vegan Status: Yes โ€“ fermentation or synthetic

Halal Status: Yes

Source Notes: Fermentation-derived from glucose or synthetic. among the safest chemical exfoliants available.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 โ€“ very low

Comedogenicity Rating: 0/5 โ€“ non-comedogenic

Sensitivity Concerns: No photosensitization; no stinging; suitable for very sensitive skin.

Safe for Sensitive Skin: Yes โ€“ ideal for sensitive, reactive, rosacea, and eczema-prone skin; no photosensitization

SAFETY & COMPATIBILITY

Safety Profile: Exceptional safety profile. no photosensitization. ewg score: 1.

Works Well With: Ceramides,niacinamide,hyaluronic acid,soothing actives

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Phas have molecular weights 2โ€“3ร— larger than ahas, limiting penetration to superficial layers. combined humectant and antioxidant properties make them uniquely well-tolerated while providing meaningful exfoliation.

Last Verified: Cosing database,green & yu (2003) pha review,cir safety assessment

Primary Sources: 2026-03-12

Glycolic Acid

Common Name(s): Hydroxyacetic acid,2-hydroxyacetic acid

CAS Number: 79-14-1

DESCRIPTION

What It Does: Provides maximum aha efficacy from the smallest most penetrating alpha-hydroxy acid.

Why It's Used: The most potent aha โ€” glycolic acid's smallest molecular size provides the deepest penetration and highest efficacy of any alpha-hydroxy acid for exfoliation and anti-aging.

How It Works: Smallest aha (mw 76) provides deepest stratum corneum penetration. disrupts corneodesmosomes reducing cohesion. stimulates fibroblast collagen i and iii synthesis. efficacy is ph-dependent โ€” free acid fraction determines activity.

Typically Found In: Chemical peels,body lotions,anti-aging serums,exfoliating toners

TECHNICAL DETAILS

Primary Category: Active ingredient โ€“ primary aha

Secondary Functions: Brightening,collagen stimulation

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 1%โ€“10% cosmetic; higher professional

SOURCING & ETHICS

Vegan Status: Yes โ€“ synthetic or fermentation-derived

Halal Status: Yes

Source Notes: Fermentation-derived or synthetic. ph must be โ‰ค4.0 for aha activity.

SKIN COMPATIBILITY

Irritancy Rating: 2/5 โ€“ low to moderate

Comedogenicity Rating: 0/5 โ€“ non-comedogenic

Sensitivity Concerns: Photosensitizing โ€“ mandatory spf use. start at low frequency.

Safe for Sensitive Skin: Use with caution โ€“ spf required

SAFETY & COMPATIBILITY

Safety Profile: Eu cosmetics: max 10% leave-on, ph โ‰ฅ3.5, mandatory sun protection advisory. professional peel concentrations regulated separately.

Works Well With: Niacinamide,ceramides,hyaluronic acid,spf

Avoid Combining With: Retinol in same step; multiple exfoliants simultaneously

SCIENTIFIC NOTE

Glycolic acid's ph-dependent efficacy is critical: at ph 3.0 ~100% is in the free acid (membrane-permeable) form; at ph 3.5 ~70%; at ph 4.0 ~50%. the eu ph โ‰ฅ3.5 requirement reduces free acid proportion, lowering efficacy but also reducing irritation โ€” why professional peel concentrations at lower ph are far more active than equivalent cosmetic concentrations.

Last Verified: Cosing database,eu aha guidelines,cir safety assessment

Primary Sources: 2026-03-12

Polysorbate 20

Common Name(s): Tween 20,poe(20) sorbitan monolaurate

CAS Number: 9005-64-5

DESCRIPTION

What It Does: Solubilizes fragrance oils and other lipophilic ingredients into water-based formulations.

Why It's Used: Standard fragrance solubilizer for water-based formulations โ€“ the industry standard for incorporating oil-soluble fragrances and actives into aqueous systems without separate oil phase.

How It Works: Hlb ~16.7 provides strong solubilization capacity for oils in water. laurate (c12) chain provides milder skin interaction than higher-hlb polysorbates. polyoxyethylene chains (20 eo units) provide high water solubility. effective solubilizer at 3-4:1 polysorbate:fragrance ratio.

Typically Found In: Toners,micellar waters,fragrance-containing aqueous products

TECHNICAL DETAILS

Primary Category: Functional ingredient โ€“ sorbitan ester emulsifier/solubilizer

Secondary Functions: Skin conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.5%โ€“5%

SOURCING & ETHICS

Vegan Status: Conditional โ€“ sorbitol from plant, peg from petroleum

Halal Status: Yes

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 โ€“ very low

Comedogenicity Rating: 0/5 โ€“ non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Same peg 1,4-dioxane concern as all peg compounds. quality-grade ps-20 should be tested for impurities.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Polysorbate 20's optimal solubilization ratio (3-4 parts ps-20 per part fragrance oil) is lower than expected from pure hlb theory. this efficiency arises from polysorbate's formation of very small, stable oil-in-water microemulsions (droplets <50nm) rather than conventional emulsions, providing optically clear, thermodynamically stable fragrance incorporation that conventional emulsifiers cannot achieve.

Last Verified: Cosing database,cir safety assessment

Primary Sources: 2026-03-12