The Vitamin C 23 Serum — Reddit Reviews
by COSRX
Updated November 10, 2026
23% pure vitamin C fades dark marks and brightens; oxidizes quickly.
What the community says
A high-strength 23% ascorbic acid serum for stubborn discoloration, dullness, and post-acne marks, with panthenol and squalane adding some cushion. It suits experienced vitamin-C users; sensitive or tret-treated skin may sting, dry out, or break out.
What this means for you
What people love
- High-strength 23% pure vitamin C
- Fades post-inflammatory hyperpigmentation and dark spots
- Brightening glow can show quickly
Watch out for
Product details
Use caution
Skin Type
Product Traits
What TikTok says
From 4 TikTok videos2 sponsored, marked with outlined numbers
Sponsored creators say its 23% vitamin C gives more brightening and antioxidant protection 12, and one rates it 8/10 for stubborn dark spots 2. Unsponsored creators 34 give it 7/10 and 9/10, with one calling it powerful for dark spots and uneven skin tone 3. Creators warn that 23% vitamin C can irritate sensitive or damaged skin 3, and another says the highest score is not automatically the best choice for sensitive skin or beginners 4.
Sponsored means the creator disclosed a brand partnership or the video ran as a paid ad.
Videos open on TikTok in a new tab.
Where to buy
What the science says
Vitamin C has some evidence for fading dark patches, especially melasma, with mostly mild, brief side effects 1. Panthenol has some evidence for helping the skin barrier hold water and recover from damage 2. Vitamin C has some evidence for smoothing wrinkles and uneven tone in sun-damaged skin, though it did not clearly beat a placebo for water content 3. Panthenol has some evidence for easing dehydrated skin by cutting water loss 4.
- Vitamin C for hyperpigmentation Some evidence · 19 studies
- Panthenol for skin barrier Some evidence · 20 studies
- Vitamin C for anti-aging Some evidence · 12 studies
- Panthenol for dehydration Some evidence · 7 studies
Research context, not treatment advice. Studies are about the ingredient, not necessarily this exact product.
How we grade researchFull ingredient list · 30
COSRX The Vitamin C 23 Serum ingredients
Aqua/Water, Ascorbic Acid(23%), Butylene Glycol, Dimethicone, Panthenol, 3-O-Ethyl Ascorbic Acid, Squalane, Sodium Hydroxide, Caffeine, Sodium Hyaluronate, Sodium Metaphosphate, Adenosine, Acetyl Glucosamine, Gardenia Florida Fruit Extract, Allantoin, Dextrin, Tocotrienols, Tocopherol, Elaeis Guineensis (Palm) Oil, Arginine, Niacinamide, Pentylene Glycol, Glutathione, Helianthus Annuus (Sunflower) Seed Oil, Methyl Trimethicone, Carthamus Tinctorius (Safflower) Seed Oil, Camellia Japonica Seed Oil, Daucus Carota Sativa (Carrot) Root Extract, Glycyrrhiza Glabra (Licorice) Root Extract, Beta-Carotene
Listed in label order, highest concentration first. Linked ingredients have their own page.
Real Reddit threads — 66 mentions across 26 threads
COSRX The Vitamin C 23 Serum on Reddit, in one place — 26 threads from r/koreanskincare, r/AsianBeauty and 3 more, summarized.
“COSRX Vitamin C 23”
Mentioned
“I forgot what some of the products I've tried but here are some of what I can remember.”
Mentioned
“I've also tried other brands from other countries.”
Mentioned
“it’s a lower concentration and IMO feels more gentle and much less irritating than the 23 version.”
Mentioned
“Which form of vitamin c does cosrx have”
Mentioned
“it has 23% pure vitamin c / L-ascorbic acid”
Mentioned
“Currently popular in my circle: vt reedle shot and pdrn, innisfree retinol, round lab sunscreen, aestura, numbuzin, torriden, cosrx vitamin c 23, mediheal masks, iope retinol, d'alba sunscreen, cell fusion c sunscreen”
Mentioned
“People here don’t touch the following brands much:”
Mentioned
“Why is CosRx not popular?”
Mentioned
“Their new vit-c serum blew up last year”
Mentioned
“all due to the fact they used old IOPE formula”
Mentioned
“I’m hoping here AP will release some of their old premium formulas under Cosrx”
Mentioned
“The vitamin c serum by cosrx. Does an amazing job with brightening!”
Positive
“Oh wow so many great products to choose from but I definitely would grab a bunch of Cosrx”
Positive
“I just bought the Cosrx vit c 13 and I like it so far.”
Positive
“Cosrx vitamin c 23. I used it twice a day for about 4 months and I saw results in the first week.”
Positive
“Agree with CosRx Vit C.”
Positive
“it did brighten my skin well.”
Positive
Dupes & Alternatives
Anua
Azelaic Acid Hyaluron Redness Soothing Serum
Better for Hyperpigmentation
9 shared traits
781 mentions
