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 yet- Ships from our California warehouse
- Duties prepaid
- 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. Ships from our California warehouse, dispatched within 2 business days
You’re $100.00 away from free US shipping.
- Duties prepaid
- 30-day returns
- Free US shipping on orders of $100 or more
- Dispatched within 2 business days
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
Key actives
Salicylic Acidexfoliant
It loosens the dead cells that block pores and is used for the look of congested, oily skin. The name on the box points at it, and it is named sixteenth on this serum's own ingredient list.
Niacinamideactive
Niacinamide is vitamin B3, and it is the most studied active in Korean formulation. The panel names it fifteenth on this serum's list, beside Salicylic Acid.
Allantoinactive
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. The panel names it seventeenth on this serum's list, beside Salicylic Acid.
Gluconolactoneexfoliant
Gluconolactone is a PHA, the gentlest exfoliant class. The panel names it second on this serum's list, beside Salicylic Acid.
Lactic Acidexfoliant
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. The panel names it third on this serum's list, beside Salicylic Acid.
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.
- Ships from
- California
Duties are prepaid. Nothing is owed at delivery. Returns are accepted for 30 days, by mail.
Orders ship from our California warehouse, dispatched within 2 business days, and arrive in 3 to 5 days. Shipping is free on orders of $100 or more.
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 - 2Customs
Duty paid by us before it enters the US - 3California
Ships domestically, no international leg
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.
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.
Import duties are paid by us before the parcel reaches you, so nothing is owed at the door, 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.
Payment and security
We accept
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.
Reviews
No reviews yet. Tell us how much you love the product!
Write Reviews (opens in a new tab)We’re on gram!
Creators trying on authentic Korean skincare routines and products from us.
Rating a shelf of Dr. Althea products one by one.
Jasmine Loo · YouTube
Two hydrating serums side by side, IUNIK and Dr. Althea.
Kristin · YouTube
A walk through the Dr. Althea serum lineup and who each one suits.
auraofmahmuda · YouTube
A blunt first take on the Dr. Althea range.
Lexi Chang · YouTube
A first look at the viral 345 Relief Cream before buying.
Shelley Nayak · YouTube
A first try of the Dr. Althea serum on camera.
Hannah Ziad · YouTube
Korean-market original
The Original Korean Formula serum from Isntree, 20ml formulated with Salicylic Acid and Niacinamide, held in the United States and shipped domestically.
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.
Match the batch code on the box against the code printed on the bottle or tube itself; the two are stamped separately and should agree.
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 the key actives in this formula, quoted from the medical sources linked beside each.
BHAs like salicylic acid get really deep into the pores, whereas the water-soluble ones don't go as deep.
Samantha Stein, PA-CDermatology physician assistant, Cleveland Clinic Allantoin can tone down the dryness of the individual cells. It increases the water content of the skin, which means it helps to hydrate and moisturize.
Wilma Bergfeld, MDDermatologist, Cleveland Clinic
1 more professional perspective
Niacinamide helps reduce the appearance of pores in a few ways. By strengthening the skin barrier and improving elasticity, pores appear less noticeable and more even.
Ashlyn YankeAesthetician, Cleveland Clinic
Ask an AI assistant about this product
Ask an AI assistant about this product
Opens ChatGPT, Perplexity or Claude in a new tab with the question prefilled. Claude asks you to sign in first.