COSRX Vitamin C 13 Serum.

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Serums

Guru Score

82%

Yay

Early verdict · Few reviews so far

What the gurus are saying

Unanimous yay from 2 reviewers. Dr. Jenny Liu and CYoung both rate it highly. Top take: "This one's slightly different which is why it's on my list.", Dr. Jenny Liu.

Synthesized from 2 expert reviews · most recent take October 2026

Type

Serums

Where to buy

Ulta → Amazon → Google → iHerb →

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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.

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.