Is a higher hyaluronic acid percentage better?

Not automatically, and three percent is already high for a leave-on serum. What a humectant does depends on the whole formula and on what you layer over it, not on the headline figure by itself. Published work comparing molecular weights has found no universal winner. Read the number as useful disclosure, since COSRX states it where most brands do not, rather than as proof of a stronger outcome.

Does it contain alcohol?

Yes. Plain alcohol appears thirty-ninth out of forty-three ingredients, which places it among the smallest quantities in the bottle. It is not alcohol denat. and there is no SD alcohol. If your skin objects to any alcohol at all that is still worth knowing before buying, and worth a patch test. One reseller publishes the same list in a different order that puts alcohol considerably higher, so we have followed the brand's own ordering.

Is it fragrance-free and silicone-free?

Fragrance-free, yes. There is no parfum and no aroma compound, and we checked every entry against the EU's declarable-allergen annex without finding a single match. Nothing on the list is a plant oil either, so no scent arrives indirectly that way. Silicone-free, no. Dimethicone sits twelfth, high enough to matter if you avoid them, and it is the thing most likely to give this fluid its brief slip before it settles.

Where does it go in a routine?

After cleansing and any toner, before anything thicker. A few drops pressed over slightly damp skin covers a whole face, and twenty millilitres lasts a while at that rate. COSRX allows it morning or evening, and there is no reason to choose between them. Follow with a moisturizer, because a watery hydrating layer on its own tends to feel tight again once the water in it has gone.

What is the amino acid complex doing here?

Amino acids, betaine and the PCA salts are the same sort of small water-holding molecules skin already makes for itself, which is why brands group them under natural moisturising factor. Eight of them sit between positions twenty and thirty-two on this list. They support the hydration story rather than being the reason to buy the bottle, which remains the hyaluronate at three percent.

Does COSRX publish test results for it?

It publishes two immediate-measurement hydration figures from a trial of twenty people, taken right after application rather than after days of use. We have deliberately left them off this page. A reading taken minutes after a humectant goes on is close to a given, secondary sources disagree on how many people took part, and no other retailer reproduces the numbers at all.

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COSRX

COSRX The Hyaluronic Acid 3 Serum 20ml

Hydrating
Barrier lipids
Lightweight
Fragrance-free

20ml ·€16.00

Hydrating

Barrier lipids

Lightweight

Fragrance-free

PRODUCT DETAILS

The 3 in the name is a strength, not a tally. COSRX prints Sodium Hyaluronate(3%) fifth on its own ingredient list, and that entry is the only hyaluronate the bottle contains: one material at a declared concentration rather than three separate ones. The rest of the range is numbered the same way, with the Alpha-Arbutin 2 and the Retinol 0.3 both carrying their figure as a percentage inside the list itself.

The other half of the front label, Amino Acids + Ceramide NP, is the part shoppers tend to skip past. Eight free amino acids sit between positions twenty and thirty-two, with betaine, sodium PCA, sodium lactate and PCA scattered among them. Ceramide NP lands at thirty-three next to cholesterol and phytosphingosine, which is the grouping that usually signals a real lipid set rather than a token inclusion.

Texture follows the order. Water leads, then butylene glycol, propanediol and glycerin, so what comes out of the dropper is a thin clear fluid that sinks in quickly and leaves very little on the surface. Twenty millilitres is a small bottle and a few drops is the intended dose, so it lasts longer than the size suggests.

Two things are worth knowing first. Dimethicone sits twelfth, so this is not a silicone-free formula, and plain alcohol appears thirty-ninth of forty-three, low down but present. No fragrance, no parfum and no plant oil appears anywhere on the list.

Learn more

GOES WELL WITH

100 Reedle Shot Stick Pouch€7.88

1025 Dokdo Cleanser€10.99

1025 Dokdo Eye Cream€20.88

1025 Dokdo Lotion€13.98

1025 Dokdo Sleeping Pack€14.98

1025 Dokdo Sun Cream€17.98

1025 Dokdo Cream€23.00

1025 Dokdo Pad€18.99

One hyaluronate at a concentration the brand is willing to print, supported by the small water-holding molecules skin already makes.

Three percent sodium hyaluronate, stated
Eight free amino acids
Ceramide NP with cholesterol
Thin enough to layer under anything

Key Ingredients

Clear hydrogel spheres and droplets on a pale lilac background.

Hyaluronic Acid

Helps hydrate and visibly plump the skin.

Overlapping ivory wax-like layers on a warm blush background, representing ceramide barrier lipids.

Ceramides

Barrier-supporting lipids that help reduce moisture loss and ease visible dryness.

Clear serum pooled beneath a glass pipette, spread thin enough that small bubbles show through it.

Concerns & Benefits

Your Concerns

1
Dehydration
Skin that reads thirsty again an hour after cleansing however much you apply.
2
Skin Barrier
Skin that has begun reacting to steps it tolerated without complaint a month ago.

How To Use

1After cleansing and any toner, drop a few beads onto your fingertips and press them across the face, beginning at the nose and cheeks and moving outward. Allow a moment for it to sink in before whatever comes next.
2Twice daily is fine, and so is once at either end of the day. Something richer should go over the top, since a watery layer like this one sits better underneath an occlusive, and that matters more in heated rooms and dry weather.
3If your skin flares readily, try a little along the jawline for a day or two before committing to the whole face. Keep it off the eyes themselves, and stop if it stings.

The same bottle tilted among pale blue spheres of varying sizes, floating against a soft blue backdrop.

Frequently asked questions

Does the 3 mean three types of hyaluronic acid?

No, it is a concentration. COSRX's own ingredient list prints Sodium Hyaluronate(3%) in fifth place, and that single entry is the only hyaluronate in the bottle. The rest of the range is named the same way, with Alpha-Arbutin 2 and Retinol 0.3 both carrying their number as a percentage. Counting forms would not settle much anyway, since a longer tally does not establish better hydration without a direct comparison between finished products.

Customer reviews

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COSRX The Hyaluronic Acid 3 Serum 20ml | Sleepy Hello

COSRX

COSRX The Hyaluronic Acid 3 Serum 20ml

Hydrating
Barrier lipids
Lightweight
Fragrance-free

COSRX The Hyaluronic Acid 3 Serum 20ml

20ml ·€16.00

Hydrating

Barrier lipids

Lightweight

Fragrance-free

PRODUCT DETAILS

Learn more

GOES WELL WITH

100 Reedle Shot Stick Pouch€7.88

1025 Dokdo Cleanser€10.99

1025 Dokdo Eye Cream€20.88

1025 Dokdo Lotion€13.98

1025 Dokdo Sleeping Pack€14.98

1025 Dokdo Sun Cream€17.98

1025 Dokdo Cream€23.00

1025 Dokdo Pad€18.99

One hyaluronate at a concentration the brand is willing to print, supported by the small water-holding molecules skin already makes.

Three percent sodium hyaluronate, stated
Eight free amino acids
Ceramide NP with cholesterol
Thin enough to layer under anything