COSRX

COSRX Vitamin C 13 Serum.

Serums

About this product

A vitamin C face serum from COSRX with 13% ascorbic acid, designed to brighten the skin and help improve radiance. It is also made in a stronger 23% version.

Guru Score

82%

Yay

Early verdict · Few reviews so far

What the gurus are saying

The 13% is the number to know: it's pure ascorbic acid at a strength gurus call effective, and they say it brightens, defends against environmental stress and supports collagen. COSRX also makes a 23%, but beginners are pointed to the 13%, which has a lighter texture and less sting, since higher isn't always better and more concentration can mean more irritation. Fading dark spots takes consistent use.

Synthesized from 2 expert reviews · most recent take October 2026

What they liked

Pure ascorbic acid form
13% concentration within effective range

What they flagged

Nothing. None of the experts who reviewed it raised a problem.

Type

SerumsDrops & dropper

Where to buy

Ulta → Amazon → Google → iHerb →

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What the experts use it for.

The concerns the experts tie this product to, in their own words. Paid and founder takes don't count.

Dull skin1 expert

“So it helps to brighten, helps to defend against oxidative stress from the environment at the same time supporting collagen and improving radiance of your skin.”

Dr. Jenny Liu, watch at 7:58

What the gurus are saying.

Every take we've logged from this product's reviews across YouTube. Click any row to watch the moment they said it.

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Dr. Jenny Liu

324k subs

✓Yay

"This one's slightly different which is why it's on my list. It's got 13% ascorbic acid and that is the pure vitamin C derivative that works through everything, versus many other skincare brands will have ethylated ascorbic acid which really does the brightening. But 13% is within the effective concentration which is really great. So it helps to brighten, helps to defend against oxidative stress from the environment at the same time supporting collagen and improving radiance of your skin."

CYoung

96k subs

✓Yay

"[COSRX] vitamin C comes in 13% and 23%. [...] I don't understand why offline stores only carry the 23% because it can sting quite a bit. For beginners I recommend the 13%. I've seen positive reviews from skincare experts in Korea and globally about fading dark spots with consistent use. [...] The 13% has a lighter texture while the 23% feels richer and maybe too oily for some. Higher isn't always better, since more concentration can mean more irritation."

Frequently asked.

What is COSRX Vitamin C 13 Serum?

A vitamin C face serum from COSRX with 13% ascorbic acid, designed to brighten the skin and help improve radiance. It is also made in a stronger 23% version.

Is COSRX Vitamin C 13 Serum worth it?

Yes. All 2 gurus who reviewed it give it their stamp of approval, for a Guru Score of 82%.

What is COSRX Vitamin C 13 Serum's Guru Score?

COSRX Vitamin C 13 Serum holds a Guru Score of 82%. That is our read on how warmly the experts talk about it, based on the verdicts of 2 expert reviewers we have collected.