COSRX
The AHA 2 BHA 2 Blemish Treatment Serum
A blemish serum carrying glycolic acid and salicylic acid, the AHA and BHA behind the name, though this bottle's own list does not declare a percentage for either.
No reviews yet- Korean-market formula
- Ships from California or direct from Korea
- Korean barcode and batch code intact
- Suited to
- DryDehydratedTexturedCongested
- Helps with
- DehydrationRough surface textureUneven tone and dullnessExcess oil
Sold out.
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- 30-day returns
- Free US shipping on orders of $100 or more
- Tracked delivery to your door
How it works
An acid serum is the one step in a routine that should not be doubled up, and this one carries two acid types at once: glycolic acid and salicylic acid, with gluconolactone behind them. It goes on in the evening after cleansing, before moisturizer, on skin that is dry rather than damp. Zinc PCA, allantoin and dipotassium glycyrrhizate are on the same list, which is what keeps a short acid formula wearable. Skin that looks congested and marked in the same places is the case it fits. Two or three evenings a week to start, and sunscreen the next morning is part of using an acid at all.
Inside the formula
Inside the formula
- 4Glycolic Acid
- 5Salicylic Acid
- 9Sodium Hyaluronate
Where each key active sits on the declared ingredient list, by entry number. Position is proportion: the further forward, the larger its share.
How to use
- Use the AHA 2 BHA 2 Blemish Serum in the evening, after cleansing and before moisturizer.
- A thin layer over the areas that want it, or the whole face, kept clear of the eyelids and lips.
- Wait a minute, then follow with a plain moisturizer the same evening.
- Two or three evenings a week to start. Do not use it in the same routine as another acid or a retinoid.
COSRX The AHA 2 BHA 2 Blemish Treatment Serum
What do the numbers in AHA 2 BHA 2 actually refer to on the ingredient list?
Glycolic acid sits fourth on this serum's list and salicylic acid fifth, right after the base solvents, on a comparatively short list of only seventeen entries. Neither acid carries a declared percentage on this bottle's own ingredient panel, so the numbers in the name are not something we can confirm as an exact concentration. What is confirmed is that both acids sit high on a short list, ahead of the calming and hydrating ingredients that follow.
Is this too strong for skin new to chemical exfoliants?
Glycolic acid and salicylic acid both sit near the front of the list, which is a real signal that this is formulated as an active exfoliating treatment rather than a gentle everyday serum. Zinc PCA, allantoin, sodium hyaluronate, and dipotassium glycyrrhizate follow to offset some of the dryness acids can cause. Anyone new to combining an AHA and a BHA in one product should start with a thin layer a few nights a week rather than applying it nightly from the start.
Will blemishes clear up after one use of this serum?
Exfoliating acids work by encouraging surface turnover with repeated, spaced-out use, not by clearing a blemish after a single application. Gluconolactone, a gentler PHA-family ingredient, sits alongside the two acids and supports the same gradual resurfacing process over time. Using it consistently a few nights a week and watching how skin responds over several weeks is the realistic way to judge whether it is working.
Can I apply moisturizer right after this serum?
Yes, applying a moisturizer afterward is standard practice with an acid treatment like this one, since sodium hyaluronate on this list only partially offsets the drying effect glycolic and salicylic acid can have. Nothing here is known to conflict with a standard moisturizer or sunscreen used in the same routine. Avoid layering it the same night as a separate strong acid or retinoid product, since stacking actives raises the chance of irritation.
How do I verify this serum is the genuine Korean-market formula?
This bottle's own barcode, 8809598455696, is a real EAN tied to this exact product, so checking that number against your packaging is a useful first step. COSRX additionally verifies units through its own system: enter the batch number and expiration date printed on your unit at the checking page on cosrx.com, read directly from the box itself. Combining the barcode check with the batch verification is the more complete way to confirm authenticity.
Not on the ingredient list below: fragrance or parfum, denatured or SD alcohol, essential oils, silicones, parabens, sulfate surfactants, mineral oil or petrolatum and added color.
Full INCI (17): 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
Ingredient list read from inkeedecoder.com on 18 August 2026.
17 of 17 explained
- Water solvent
- Water is the base almost every serum, toner and cream is built on. It dissolves the water-loving ingredients and sets how light the finished texture feels. On an INCI list it is usually first, which only means it is the largest single ingredient by weight.
- Propanediol humectant
- Propanediol is a plant-derived glycol used in place of propylene glycol. It hydrates, carries actives into solution, and gives a lighter, less sticky slip than glycerin at the same strength.
- Polysorbate 20 emulsifier
- Polysorbate 20 is a solubiliser: it dissolves small amounts of oil or fragrance into a watery formula so nothing separates or floats.
- Glycolic Acid exfoliant
- Glycolic Acid is the smallest AHA, which is why it is also the most penetrating and the most likely to sting. It loosens the bonds between dead surface cells and is used for the look of dullness and rough texture.
- Salicylic Acid exfoliant
- Salicylic Acid is a BHA, and the only common exfoliant that is oil soluble, so it can work inside a pore rather than only on the surface. It loosens the dead cells that block pores and is used for the look of congested, oily skin.
- Gluconolactone exfoliant
- Gluconolactone is a PHA, the gentlest exfoliant class. Its molecule is too large to penetrate quickly, so it smooths the surface without the sting of an AHA, and it is a humectant at the same time.
- Zinc PCA active
- Zinc PCA pairs zinc with the humectant PCA. It is used in oily and blemish-prone formulas for the look of shine and visible pores, and it hydrates at the same time.
- Allantoin active
- Allantoin is a comfrey-derived compound used to condition skin and soften the outer layer so it feels smoother. It is one of the standard additions to a formula built for easily irritated skin.
- Sodium Hyaluronate humectant
- Sodium Hyaluronate is the salt of hyaluronic acid, and it is what most products labelled hyaluronic actually contain. The salt dissolves more readily and the molecule is smaller, so it sits in the outer layer of skin rather than only on top of it.
- Sodium Hydroxide pH adjuster
- Sodium Hydroxide is a strong base used in traces to bring an acidic formula up to skin-friendly pH. None of it remains as itself once the formula is neutralised.
- Dipropylene Glycol humectant
- Dipropylene Glycol is a glycol used as a solvent and a light humectant. Its main job is keeping the rest of the formula dissolved and the texture fluid rather than adding hydration of its own.
- Hydroxyacetophenone preservative booster
- Hydroxyacetophenone is an antioxidant that also strengthens a preservative system, so a formula needs less traditional preservative. Korean formulas pair it with 1,2-hexanediol constantly.
5 more explained
- Caprylyl Glycol preservative booster
- Caprylyl Glycol is a glycol that conditions skin and, more importantly, strengthens a preservative system so less of the traditional preservative is needed. It appears in most modern formulas built without parabens.
- Ethylhexylglycerin preservative booster
- Ethylhexylglycerin softens skin and boosts a preservative system, which is why it is nearly always sitting beside phenoxyethanol or 1,2-hexanediol. It also cuts down the odour bacteria produce, so it turns up in deodorising products.
- Dipotassium Glycyrrhizate active
- Dipotassium Glycyrrhizate is a water-soluble salt derived from licorice root. It is the licorice fraction Korean formulas use for the look of redness, and it is far more stable in water than the whole extract.
- 1,2-Hexanediol humectant
- 1,2-Hexanediol is a glycol used for two reasons: it holds water like glycerin, and it makes a formula harder for microbes to live in, so less traditional preservative is needed. Korean formulas use it heavily for that second reason.
- Disodium EDTA chelator
- EDTA is a chelator: it locks up trace metal ions from water and packaging that would otherwise turn a formula cloudy, off-colour or rancid. It does nothing to skin and appears at a fraction of a percent.
- Market
- Korean market, the version sold in Korea
- EAN (barcode)
- 8809598455696
- Made in
- Republic of Korea
- Category
- Serum & Ampoule
- Actives
- Allantoin, Glycolic Acid, Licorice Root, Salicylic Acid, Sodium Hyaluronate, Zinc PCA
- Ships from
- California or Korea
Orders ship from California or direct from Korea with tracked delivery to your door, and both routes carry the same Korean-market release. Shipping is free on orders of $100 or more. Returns are accepted for 30 days, by mail.
We split shipments free, so one out-of-stock item never holds up the rest of your order.
Where this unit came from
- 1Seoul
Bought as Korean-market stock - 2Barcode
Listed against the Korean barcode on its box - 3California or Korea
Ships to you from either, as the same Korean-market release
We stock the version of a formula that is sold in Korea, not the release a brand prepares for another market under the same name. The barcode in the specification above is the Korean-market one and it is printed on the box you receive.
Every unit keeps its original barcode and batch code intact, so the unit in your hands can be checked against the brand’s own records.
Every order ships from California or direct from Korea, and returns run for 30 days.
Every claim on this page traces to the unit in the box, the barcode, the batch code and the price you can read for yourself.
Key benefits
- Glycolic acid is the AHA on the list; salicylic acid is the BHA.
- Neither acid carries a declared percentage on this bottle's own ingredient list.
- Sodium hyaluronate and allantoin sit further down for a calmer feel.
- Dipotassium glycyrrhizate, a licorice-derived ingredient, rounds out the calming base.
Key actives
9Sodium Hyaluronate
a humectant that offsets the dryness acids can cause
Worth knowing
- This formula carries an active acid, so pairing it with another exfoliant in the same routine is worth spacing out.
Reviews
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COSRX The AHA 2 BHA 2 Blemish Treatment Serum
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COSRX, Korean-market original
AHA BHA blemish treatment serum, with Glycolic and Salicylic Acid.
Verify your unit when it arrives
Verify your unit when it arrives
Korean-market stock with the original barcode and batch code intact, exactly as it left Korea.
COSRX verifies units itself. Find the verification page on cosrx.com and enter the batch number and expiration date printed on your unit. Read them off the package rather than from us, which is the point.
Source: COSRX FAQ
On the unit itself
- The Korean-market barcode, unaltered from the retail package.
- The manufacturer’s batch code, exactly as the maker printed it.
정품Genuine article, Korean-market stock
What professionals say
What professionals say
What skin-care professionals say about skin care, quoted from the medical sources linked beside each.
As we age, the glue that holds our skin cells together becomes denser, which slows down the natural cell turnover process.
Samantha Stein, PA-CDermatology physician assistant, Cleveland Clinic Pretty much every step of a Korean skin care routine is going to have some component of hydration.
Alok Vij, MDDermatologist, Cleveland Clinic
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