Salicylic acid (BHA) is recognized globally for its ability to penetrate pores, dissolve sebum, and address congestion. However, Korean skincare approaches salicylic acid formulation differently than Western brands. Regulatory restrictions in South Korea limit pure salicylic acid concentrations, leading Korean chemists to develop alternative forms that deliver similar results with less irritation.
This article examines the Korean approach to BHA: the use of betaine salicylate, the role of gentler PHAs and AHAs in combination formulas, and the products that represent this formulation philosophy. The focus is on how these products function within a layered routine designed for acne-prone skin without compromising barrier health.
Salicylic Acid: Function and Limitations
Salicylic acid is a beta hydroxy acid (BHA) that differs from alpha hydroxy acids (AHAs) in one critical way: it is oil-soluble. This allows it to penetrate sebum-filled pores and exfoliate from within, making it particularly effective for oily and congested skin. While AHAs work on the skin surface, BHA works inside the pore.
However, traditional salicylic acid formulations carry drawbacks. At effective concentrations (typically 2%), salicylic acid can be drying and irritating, especially for sensitive or barrier-compromised skin. Western formulations often compensate by adding heavy moisturizers or silicones, which can create residue or feel occlusive. Korean formulations take a different route: reformulating the acid itself.
Why Korean regulations matter
Korean skincare regulations restrict salicylic acid concentrations in over-the-counter products. This limitation pushed Korean formulators to develop alternative BHA derivatives that achieve similar results within regulatory boundaries. The most prominent alternative is betaine salicylate — a compound that combines salicylic acid with betaine, a naturally derived humectant. The result is a gentler BHA that exfoliates while providing hydration.
Betaine Salicylate: The Korean BHA Standard
Betaine salicylate is not simply salicylic acid diluted with filler. It is a molecularly distinct compound that behaves differently in formulation and on skin. The combination of salicylic acid's exfoliating properties with betaine's humectant qualities creates an ingredient that addresses congestion while supporting hydration.
Betaine salicylate is approximately twice as gentle as pure salicylic acid. A 4% betaine salicylate product delivers comparable exfoliation to a 2% salicylic acid product, but with reduced irritation potential. This makes betaine salicylate particularly suitable for daily use, sensitive skin, or layered routines where multiple actives are combined.
How betaine salicylate differs from salicylic acid
Traditional salicylic acid requires an acidic pH (3-4) to function optimally. Betaine salicylate, however, is less pH-dependent and can work effectively at a higher pH (around 4.5-5.5). This higher pH range is gentler on the skin barrier, reducing the risk of irritation while maintaining exfoliating efficacy. The presence of betaine also adds osmolyte properties, helping skin cells regulate water balance and resist stress.
Combining AHA, BHA, and PHA: The Korean Multi-Acid Strategy
Korean skincare often combines multiple exfoliating acids in a single product. While this may seem aggressive, the strategy is carefully balanced: each acid operates at a different skin level, and lower individual concentrations reduce irritation risk while maintaining overall efficacy.
The typical combination includes:
- AHA (Alpha Hydroxy Acid): Works on the skin surface to improve texture and tone. Common AHAs include glycolic acid and lactic acid.
- BHA (Beta Hydroxy Acid): Penetrates pores to dissolve sebum and address congestion. Typically betaine salicylate in Korean formulas.
- PHA (Polyhydroxy Acid): A larger-molecule acid that exfoliates gently without penetrating deeply. Suitable for sensitive skin. Common PHAs include gluconolactone and lactobionic acid.
When formulated together at controlled concentrations, these acids provide comprehensive exfoliation across multiple skin layers without the harshness of a single high-concentration acid. This approach aligns with Korean skincare's preference for gentle, cumulative results over aggressive single treatments.
COSRX: Pioneering Gentle BHA Formulation
When discussing Korean BHA products, COSRX consistently appears as the reference standard. The brand built its reputation on minimalist formulas using betaine salicylate instead of traditional salicylic acid. COSRX products demonstrate how effective BHA can be when formulated with barrier support rather than barrier stripping in mind.
COSRX formulations typically feature short ingredient lists, transparent concentrations, and pH levels optimized for efficacy without irritation. The brand's approach — using willow bark water as a base instead of plain water, combining BHA with hydrating ingredients like niacinamide and hyaluronic acid, and avoiding unnecessary irritants — represents the Korean BHA philosophy in practice.
Why COSRX dominates the BHA category
COSRX succeeded in the BHA category because their products deliver results without the common side effects of traditional salicylic acid products: dryness, tightness, or excessive peeling. Users with sensitive or reactive skin who cannot tolerate Western BHA formulations often find COSRX products workable. This accessibility, combined with proven efficacy, made COSRX the entry point for many into chemical exfoliation.
Product Comparison: Korean BHA Formulations
The table below compares four Korean products that represent different approaches to BHA formulation — from single-acid treatments to multi-acid combinations.
| Product | Type | Active Acids | Key Features | Best For |
|---|---|---|---|---|
| COSRX BHA Blackhead Power Liquid | Treatment | 4% Betaine Salicylate | Willow bark base, niacinamide, minimal ingredients | Oily Blackheads |
| COSRX AC Collection Calming Liquid Mild | Toner | 0.2% BHA + 0.2% PHA | 85.6% green tea water, Centella, gentle daily use | Sensitive Acne-Prone |
| COSRX AHA BHA Clarifying Treatment Toner | Toner | AHA + BHA blend | Prepares skin for actives, mineral water base | Daily Prep All Types |
| Some By Mi AHA BHA PHA 30 Days Miracle Cream | Moisturizer | AHA + BHA + PHA | 70.78% Centella, 10,000ppm tea tree, ceramides | Acne-Prone Barrier Support |
The Products That Define Korean BHA
COSRX BHA Blackhead Power Liquid — The Concentrated Treatment
The COSRX BHA Blackhead Power Liquid contains 4% betaine salicylate in a willow bark water base. Willow bark is a natural source of salicylates, providing a botanically supported foundation for the active ingredient. The formula includes niacinamide for brightening and pore refinement, panthenol for barrier support, and sodium hyaluronate for hydration.
This product is designed for targeted use: 2-3 times per week initially, building to daily use as skin adapts. The texture is lightweight and absorbs quickly without residue. The pH sits around 4.0-4.5, optimized for betaine salicylate efficacy. For those addressing persistent congestion, visible blackheads, or enlarged pores, this product delivers consistent results when used correctly.
COSRX AC Collection Calming Liquid Mild — The Daily Gentle Option
The COSRX AC Collection Calming Liquid Mild combines 0.2% BHA (betaine salicylate) with 0.2% PHA (gluconolactone) in a base of 85.6% green tea water. This lower concentration makes it suitable for daily use, even on sensitive or reactive skin. The green tea base provides antioxidant protection and helps regulate sebum production.
Centella-derived actives (asiaticoside, asiatic acid, madecassic acid) offer calming benefits, making this formula particularly appropriate for acne-prone skin that tends toward inflammation. Tea tree oil provides additional antimicrobial support. The combination of gentle exfoliation, calming ingredients, and sebum regulation makes this toner an effective daily maintenance product for those managing ongoing breakouts.
COSRX AHA BHA Clarifying Treatment Toner — The Preparation Step
The COSRX AHA BHA Clarifying Treatment Toner is formulated with low concentrations of both AHA and BHA — not as an exfoliating treatment, but as a pH-adjusting toner that prepares skin for subsequent active treatments. The mineral water base provides a clean foundation while the acids gently balance the skin's pH after cleansing.
This toner is designed for daily use as part of a multi-step routine. It enhances the efficacy of serums and treatments applied afterward by optimizing skin pH and removing residual impurities that cleansing may have missed. The formula is particularly useful for those using multiple actives in their routine, as it creates an ideal environment for absorption.
Some By Mi AHA BHA PHA 30 Days Miracle Cream — The Exfoliating Moisturizer
The Some By Mi AHA BHA PHA 30 Days Miracle Cream represents an innovative approach: combining gentle exfoliating acids with intensive moisturization. The formula contains 70.78% Centella Asiatica extract, 10,000ppm tea tree leaf water, and a blend of AHA, BHA, and PHA in a creamy base.
This product addresses a common challenge with acid-based treatments: maintaining adequate hydration and barrier support while exfoliating. The high Centella concentration provides calming and reparative benefits, while ceramides and niacinamide support barrier function. The acids work to prevent congestion and improve texture, while the cream base delivers moisture. For those who want the benefits of chemical exfoliation without adding a separate treatment step, this all-in-one approach is functionally efficient.
Using BHA Products in a Korean Routine
BHA products are most effective when integrated correctly into a broader routine. The Korean approach emphasizes gradual introduction, proper layering, and barrier maintenance.
Introduction and frequency
Start with the lowest concentration and frequency. For concentrated treatments like the COSRX BHA Blackhead Power Liquid, begin with once or twice per week. For gentler formulas like the AC Collection toner, daily use may be appropriate from the start. Increase frequency gradually based on how skin responds. Signs of over-exfoliation include redness, tightness, increased sensitivity, or paradoxical increases in oil production.
Layering and wait times
BHA products are typically applied after cleansing and before other treatments. For maximum efficacy, allow 15-20 minutes before applying subsequent products. This wait time allows the acid to work at its optimal pH without being neutralized by other formulations. However, if irritation occurs, reduce or eliminate the wait time — barrier health takes priority over theoretical efficacy.
Always follow with hydration and barrier support
BHA products should never be the final step. Follow with hydrating layers (essences, serums) and a protective moisturizer. Even oily skin requires moisture after exfoliation. Skipping this step can lead to barrier compromise, which paradoxically worsens the conditions BHA is meant to address.
Actionable Summary
The Korean approach to salicylic acid prioritizes efficacy with gentleness. By using betaine salicylate instead of pure salicylic acid, combining multiple acids at lower concentrations, and formulating with barrier-supporting ingredients, Korean BHA products deliver results without the harshness associated with traditional formulations.
COSRX established the standard for Korean BHA products through minimalist formulas that work. Their BHA Blackhead Power Liquid remains the benchmark concentrated treatment, while their AC Collection toner offers a gentler daily option. For those seeking multi-functional products, Some By Mi's Miracle Cream combines exfoliation with intensive barrier support in a single step.
The key to success with BHA is gradual introduction, proper layering, and consistent barrier maintenance. Start slowly, increase frequency based on tolerance, and always follow acids with hydration and moisturization. Results accumulate over weeks and months — not overnight.
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