COSRX The Vitamin C 23 Serum 20ml
A 20ml ascorbic acid serum for uneven tone and dullness, for morning use by anyone whose skin can take a strong formula.
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- Suited to
- Normal skinCombination skinOily skin
- Helps with
- Uneven skin toneSkin that looks dullA daily morning antioxidant step
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- Dispatched within 2 business days
How it works
This is the strong end of the tone shelf, and the tingle most people feel on application is the honest signal of that rather than a fault. It is a morning serum, both because the antioxidant side of it earns its place before a day out and because it sits happily under sunscreen. The small bottle is deliberate: an ascorbic acid formula is best used within a few months of opening rather than kept for a year. That is the difference from a milder derivative serum, which is comfortable from day one and keeps longer but works more gradually. What you can judge is whether the face reads clearer and more even in the same light after a month.
Key benefits
- Ascorbic Acid sits near the top on this product's own ingredient list, a vitamin C derivative included for its brightening, antioxidant role.
- A multifunctional glycol that carries moisture and helps preserve the formula, and Butylene Glycol is right there in this product's ingredient list, near the top.
- On this formula's own list, Panthenol shows up near the top. It is a barrier-supporting provitamin that eases surface roughness.
Key actives
Ascorbic Acid
The reason the bottle exists, and the ingredient that accounts for both the results people buy it for and the tingle on application.
3-O-Ethyl Ascorbic Acid
A more stable relative on this list, sitting alongside the pure form, which is an unusual and deliberate pairing in a tone serum.
Niacinamide
On this list at a position that matters, adding a second angle on tone to a formula already built around the first.
Glutathione
Present on this list, one of the better established tone ingredients in Korean formulas and a sensible companion here.
Panthenol
A comfort humectant on this list, included so a strong morning serum is a little easier on the skin than it would otherwise be.
Will it sting?
Most people feel a tingle for up to a minute, which is normal for the strong end of this category. Stinging that does not settle is a signal to stop and choose a milder derivative serum instead. Starting every other morning for a fortnight makes the difference for most skin.
Where does it go in my routine?
In the morning, after the toner and before the moisturizer, with sunscreen as the last layer. The antioxidant side earns its place before a day out, and it sits under sunscreen without trouble. Wait a minute after applying before the next layer goes on.
How long does it keep?
Use it within a few months of opening and keep the bottle closed and out of the light, since this kind of formula does not keep as long as a milder derivative. That is why the bottle is small. If it darkens noticeably, replace it rather than pushing on with it.
Can I use it with a retinoid?
Not in the same sitting. Keep this to mornings and the retinoid to nights, which suits both, since a retinoid is broken down by light anyway. Stacking them together is how people end up flushed and peeling and then abandon both without learning which one suited them.
Is this the Korean-market formula?
Yes. This is the Original Korean Formula 20ml bottle, the same one sold on Korean shelves.
- 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
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How to use
- Start every other morning for the first fortnight rather than daily, since this is the strong end of the category.
- Apply after the toner on slightly damp skin, pressing a small amount over the face.
- Wait a minute for the tingle to settle, then apply your moisturizer and finish with sunscreen.
- Do not use it in the same sitting as an exfoliating product or a retinoid, and keep the bottle closed and out of the light.
Worth knowing
- Expect a tingle on application, and stop if it turns into stinging that does not settle within a minute.
- Sensitive skin should choose a milder derivative serum instead of starting here.
- Use it within a few months of opening and keep it closed and away from light.
Reviews
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Korean-market original
A 20ml ascorbic acid serum for dull, uneven looking skin, stocked in the Original Korean Formula.
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.
Using topical vitamin C can result in less cell damage and better-looking skin.
Melissa Piliang, MDDermatologist, Cleveland Clinic Pantothenol is a common ingredient in skin care and hair products I recommend, particularly for people who are prone to dryness.
Taylor Bullock, MDDermatology resident, 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
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