Isntree
Hyper Acid 4 (AHA BHA PHA LAH) 30 Serum 20ml
Isntree Hyper Acid 4 (AHA BHA PHA LAH) 30 Serum is a 20ml serum with Salicylic Acid, used after toner and before moisturizer, morning and evening.
No reviews yet20 ml
$7.50 per 10 ml
- Korean-market formula
- Ships from California or direct from Korea
- Korean barcode and batch code intact
- Suited to
- OilyCombinationBlemish-proneNormal
- Helps with
- Rough texture on sensitised skinDull, rough surface textureDullness and an uneven-looking toneClogged pores and recurring breakouts
In stock. Arrives in 3 to 7 business days
We accept
You’re $100.00 away from free US shipping.
- 30-day returns
- Free US shipping on orders of $100 or more
- Tracked delivery to your door
How it works
The Hyper Acid 4 (AHA BHA PHA LAH) 30 Serum is a 20ml serum, used after toner and before moisturizer, morning and evening. The exfoliant it is built around is Salicylic Acid, named sixteenth on its own ingredient list. The same list carries Niacinamide, Allantoin and Gluconolactone, so the exfoliant is not the only thing on it worth naming. How much of the Salicylic Acid stays on the skin, and for how long, is decided by the serum format rather than by the list alone. This is the Original Korean Formula, the serum Isntree sells in Korea, Salicylic Acid and all.
Key benefits
- Salicylic Acid, the exfoliant this serum is built around
- Niacinamide and Allantoin on the same list, actives
- Gluconolactone and Lactic Acid on the same list, exfoliants
- Glycolic Acid and Capryloyl Salicylic Acid further down the same list
- Salicylic Acid named sixteenth on the manufacturer list printed on this page
- The Korean-market release of this serum, confirmed against its Korean barcode
Inside the formula
Inside the formula
Where does this serum go in my routine?
After toner and before moisturizer, morning and evening. Anything thinner than a serum goes on before it, and anything richer goes on after. If you are adding it to a routine you already like, give it a week on its own first, so what you see is the Salicylic Acid and not three changes at once.
Is this the Korean-market serum or a US version?
The Korean-market one, Salicylic Acid and all. We match this serum to its Korean barcode before it reaches the shelf, which is the check that tells you which market release you are holding.
What else is on the list besides Salicylic Acid?
Niacinamide, Allantoin and Gluconolactone. The order they are printed in on this serum's panel is the order on the box, so you can see where Salicylic Acid sits relative to them. Further down the same panel: Lactic Acid, Glycolic Acid and Capryloyl Salicylic Acid.
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 (26): Water, Gluconolactone (14.87%), Lactic Acid (10.12%), Methylpropanediol, Glycolic Acid (4.9%), Potassium Hydroxide, 1,2-Hexanediol, Diethoxyethyl Succinate, Glycerin, Xanthan Gum, Polyglyceryl-10 Laurate, Acacia Senegal Gum, Polyglyceryl-10 Myristate, Glyceryl Caprylate, Niacinamide, Salicylic Acid (0.1%), Allantoin, Disodium EDTA, Ethylhexylglycerin, Peat Water, Citric Acid (0.02%), Hydroxypropyl Methylcellulose, Capryloyl Salicylic Acid (0.01%), Butylene Glycol, Potassium Sorbate, Charcoal Powder
Ingredient list read from inkeedecoder.com on 10 September 2026.
25 of 26 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.
- Gluconolactone (14.87%) 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.
- Lactic Acid (10.12%) exfoliant
- Lactic Acid is a larger AHA than glycolic, so it works nearer the surface and is easier on skin, and it is a humectant as well as an exfoliant. It is the AHA of choice for dry skin.
- Methylpropanediol humectant
- Methylpropanediol is a small glycol used to hydrate and to help water-soluble actives penetrate the outer layer of skin more evenly. It leaves almost no tack, which suits watery textures.
- Glycolic Acid (4.9%) 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.
- Potassium Hydroxide pH adjuster
- Potassium Hydroxide is a strong base used in traces to raise a formula to its target pH. In a soap-style cleanser it also converts fatty acids into the surfactant that does the cleansing.
- 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.
- Diethoxyethyl Succinate solvent
- Diethoxyethyl Succinate is a solvent that helps water-resistant actives spread and sink in evenly. It also leaves a light, silky feel.
- Glycerin humectant
- Glycerin is the most used humectant in skincare. It draws water into the outer layer of skin and holds it there, and it is one of the very few ingredients whose hydrating effect is settled science rather than marketing. Higher amounts feel tacky, which is why it is usually blended.
- Xanthan Gum thickener
- Xanthan Gum is a polysaccharide made by fermenting sugar. It thickens a watery formula into a gel and holds the whole thing in suspension so nothing separates. Too much of it and a serum turns stringy, which is why it appears in fractions of a percent.
- Polyglyceryl-10 Laurate emulsifier
- Polyglyceryl-10 Laurate is a sugar-derived emulsifier and solubiliser, mild enough to be a standard choice in Korean essences. It dissolves small amounts of oil into water without any tightening feel.
- Acacia Senegal Gum film former
- Gum arabic, tapped from the acacia tree. It thickens, forms a tightening film as it dries, and holds pigments in place.
13 more explained
- Polyglyceryl-10 Myristate emulsifier
- Polyglyceryl-10 Myristate is a mild sugar-derived emulsifier used to keep oil dispersed in a watery formula.
- Glyceryl Caprylate emulsifier
- Glyceryl Caprylate is a mild emulsifier that also makes a formula less hospitable to microbes, so it is often part of a preservative-free system.
- Niacinamide active
- Niacinamide is vitamin B3, and it is the most studied active in Korean formulation. It is used at roughly 2 to 5 percent for the look of uneven tone and visible pores, and it is water soluble, stable and comfortable beside almost every other active, which is why it turns up in so many lists.
- Salicylic Acid (0.1%) 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.
- 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.
- 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.
- 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.
- Citric Acid (0.02%) pH adjuster
- Citric Acid is used in tiny amounts to bring a formula to the pH its actives need, not as an exfoliant at that level. It is an AHA, so at much higher concentrations it can also exfoliate.
- Hydroxypropyl Methylcellulose thickener
- Hydroxypropyl Methylcellulose is modified plant cellulose. It thickens water, forms a film, and stabilises foam, and it is the same material used to make capsule shells.
- Capryloyl Salicylic Acid (0.01%) exfoliant
- Capryloyl Salicylic Acid is salicylic acid with a fatty tail, sometimes sold as LHA. It stays nearer the surface than salicylic acid and works at a higher pH, so it exfoliates more evenly and more gently.
- Butylene Glycol humectant
- Butylene Glycol is a small glycol that does two jobs at once: it holds water in the top layer of skin and it dissolves plant extracts and actives that plain water cannot. It also thins a formula, which is why watery Korean essences lean on it.
- Potassium Sorbate preservative
- Potassium Sorbate is a preservative that holds off yeast and mould in acidic formulas. It is almost always used with sodium benzoate, because neither covers the whole range of microbes alone.
- Charcoal Powder absorbent
- Activated charcoal, a very porous carbon powder. Its surface binds oil and pigment, and it is what makes a mask or cleanser black.
- Market
- Korean market, the version sold in Korea
- EAN (barcode)
- 8809800940880
- Made in
- Republic of Korea
- Volume
- 20 ml
- Category
- Serum & Ampoule
- Actives
- Allantoin, Glycolic Acid, Lactic Acid, Niacinamide, Salicylic Acid
- 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.
How to use
- Start at two nights a week and only increase if the skin stays completely comfortable.
- Apply a thin layer to clean dry skin, concentrating on the rougher areas rather than the whole face.
- Follow with a plain moisturiser afterwards so the surface is not left bare.
- Do not use it on the same night as a retinoid or another acid, since stacking is what turns a routine sore.
Worth knowing
- Introduce gradually if skin is new to acid exfoliation, watching for stinging on first use.
- Introduce gradually alongside other acids to avoid overloading a routine that already exfoliates.
- Start with a lower frequency if skin is new to BHA exfoliation, since daily use can feel like too much at first.
- Patch test on the inner arm before a first full-face application if skin tends to react easily.
Complete the routine
- This itemIsntree Hyper Acid 4 (AHA BHA PHA LAH) 30 Serum 20ml$15.00

- The treatment step of this routineIsntree TW-REAL BIFIDA Ampoule 50ml$37.50

- Seal the routine in as the last stepIsntree C-Niacin Toning Cream 50ml$22.50

Total for 3 items$75.00
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Isntree Hyper Acid 4 (AHA BHA PHA LAH) 30 Serum 20ml
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Isntree, Korean-market original
The Original Korean Formula serum from Isntree, 20ml formulated with Salicylic Acid and Niacinamide, shipped from California or direct from Korea.
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.
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.
Your skin barrier is basically your outer layer of the skin.
Melissa Piliang, MDDermatologist, 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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