Hyper Vitamin C23 Serum 20ml
Isntree Hyper Vitamin C23 Serum is a 20ml serum with Ethyl Ascorbyl Ether, used after toner and before moisturizer, morning and evening.
No reviews yet20 ml
$17.50 per 10 ml
- Korean-market formula
- Ships from California or direct from Korea
- Korean barcode and batch code intact
- Suited to
- Dehydrated skinSensitive skinDull, uneven tone
- Helps with
- Shoppers looking for Ethyl Ascorbyl Ether in a serumRoutines that want Ethyl Ascorbyl Ether and Adenosine in one stepFilling the serum step with a Korean-market formulaAnyone who wants the Ethyl Ascorbyl Ether serum sold on Korean shelves
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 Vitamin C23 Serum is a 20ml serum, used after toner and before moisturizer, morning and evening. The vitamin it is built around is Ethyl Ascorbyl Ether, named eighth on its own ingredient list. The same list carries Adenosine, Ascorbic Acid and Tocopherol, so the vitamin is not the only thing on it worth naming. How much of the Ethyl Ascorbyl Ether 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, Ethyl Ascorbyl Ether and all.
Key benefits
- Ethyl Ascorbyl Ether, the vitamin this serum is built around
- Adenosine on the same list, an active
- Ascorbic Acid and Tocopherol on the same list, antioxidants
- Gardenia Florida Fruit Extract on the same list, a plant extract
- Polyglycerin-3 and Hydroxyethyl Urea further down the same list
- Panthenol further down the same list
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 Ethyl Ascorbyl Ether and not three changes at once.
Is this the Korean-market serum or a US version?
The Korean-market one, Ethyl Ascorbyl Ether 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 Ethyl Ascorbyl Ether?
Adenosine, Ascorbic Acid and Tocopherol. The order they are printed in on this serum's panel is the order on the box, so you can see where Ethyl Ascorbyl Ether sits relative to them. Further down the same panel: Gardenia Florida Fruit Extract, Polyglycerin-3 and Hydroxyethyl Urea.
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, Ascorbic Acid(23%), Propanediol, Betaine, 1,2-Hexanediol, Polyglycerin-3, Tromethamine, Ethyl Ascorbyl Ether, Hydroxyethyl Urea, Betula Platyphylla Japonica Juice, Ethylhexylglycerin, Adenosine, Disodium EDTA, Panthenol, Gardenia Florida Fruit Extract, Dextrin, Tocopherol
Ingredient list read from isntree-global.com on 10 September 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.
- Ascorbic Acid(23%) antioxidant
- Ascorbic Acid is pure vitamin C, the most researched form and also the least stable: it needs a low pH and airtight packaging to stay active. It is an antioxidant used for the look of dullness and uneven tone.
- 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.
- Betaine humectant
- Betaine is a sugar-beet-derived humectant that cells use to hold water. In a formula it hydrates and takes the edge off cleansers and acids, which is why it often appears alongside them.
- 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.
- Polyglycerin-3 humectant
- Polyglycerin-3 is a short chain of glycerin units used as a gentler, less sticky humectant. It also helps oils and water stay blended.
- Tromethamine pH adjuster
- Tromethamine neutralises acidic thickeners such as carbomer so they gel, and holds a formula near skin-friendly pH. It is used at a fraction of a percent.
- Ethyl Ascorbyl Ether vitamin
- A vitamin C derivative with an ethyl group on the third position, the same molecule usually written 3-O-Ethyl Ascorbic Acid. The ether makes it far more stable in water than pure ascorbic acid.
- Hydroxyethyl Urea humectant
- Hydroxyethyl Urea is a humectant that holds a lot of water for its size and stays comfortable at high levels. It is used where a formula needs to feel deeply hydrating without oil.
- Betula Platyphylla Japonica Juice plant extract
- Betula Platyphylla Japonica Juice is Asian white birch sap, tapped in spring. It is over 98 percent water with trace minerals and sugars, and Korean formulas use it in place of plain water as a hydrating base.
- 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.
- Adenosine active
- Adenosine is a nucleoside that Korea's own cosmetic authority recognises as a wrinkle-care functional ingredient, which is why it appears on so many Korean lists at a low level. It is used for the look of fine lines and is stable and well tolerated.
5 more explained
- 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.
- Panthenol humectant
- Panthenol is pro-vitamin B5: skin converts it to pantothenic acid. It is a humectant that holds water and leaves skin feeling soft and less tight, and it is one of the ingredients formulators reach for when a formula also contains something harsh.
- Gardenia Florida Fruit Extract plant extract
- Gardenia Fruit Extract is the traditional East Asian yellow dye plant. In skincare it is used as an antioxidant extract, and it can tint a formula.
- Dextrin thickener
- Dextrin is a starch fragment used to thicken and to give a formula a light, powdery finish. It is also a common carrier for powdered extracts.
- Tocopherol antioxidant
- Tocopherol is vitamin E. It is an oil-soluble antioxidant that protects the oils in a formula from going rancid and works on skin as an emollient, and it is regularly paired with vitamin C because each keeps the other going for longer.
- Market
- Korean market, the version sold in Korea
- EAN (barcode)
- 8809800940781
- Made in
- Republic of Korea
- Volume
- 20 ml
- Category
- Serum & Ampoule
- Actives
- Adenosine, Birch Sap, Panthenol, Urea, Vitamin C
- 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 with three drops every other morning and move to daily only once it feels comfortable.
- Apply after toner on skin that is barely damp, then wait a minute before the next layer.
- Always finish a morning routine that includes this with sunscreen as the last step.
- Do not layer it with an exfoliating acid in the same routine, since two sharp products at once is what causes stinging.
Worth knowing
- Patch test this serum on a small area and wait a day before using it more widely, especially with Ethyl Ascorbyl Ether on the list.
- Introduce this serum on its own for the first week, so anything your skin does is traceable to the Ethyl Ascorbyl Ether rather than to three changes at once.
Complete the routine
- This itemIsntree Hyper Vitamin C23 Serum 20ml$35.00

- 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$95.00
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Isntree Hyper Vitamin C23 Serum 20ml
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Isntree, Korean-market original
The Original Korean Formula serum from Isntree, 20ml formulated with Ethyl Ascorbyl Ether and Adenosine, 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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