COSRX’s Advanced The Vitamin C 23 Serum features a high strength 23% pure vitamin C with Super Vitamin E and Glutathione to target uneven skin tone, early signs of aging, and dullness. Ideal for experienced vitamin C users seeking visible brightening and firmer skin, it absorbs smoothly to leave the complexion more radiant, supple, and revitalized.
Size: 20ml / 0.67fl. oz
| Concern | Suitable | Key Benefit | Key Ingredient |
|---|---|---|---|
| Dull & uneven tone | Yes | Brightens and evens tone | Vitamin C (23%) |
| Dark spots & post-breakout marks | Yes | Helps dark spot care | Vitamin C + Niacinamide |
| Fine lines & early aging | Yes | Early signs of aging care | Vitamin C + Hyaluronic Acid |
| Dryness | Yes | Refines and smooths surface | Vitamin C + Allantoin |
| Lack of radiance | Yes | Restores healthy glow | Vitamin C + Super Vitamin E + Glutathione |
*Cautions*
As this product contains a high concentration of Vitamin C, we recommend avoiding use alongside Copper Peptide products, including our Blue Peptide Serum & Cream, as well as other high-concentration actives such as retinol. For best results, use them at different times of day (morning/evening) to optimize absorption and maximize the benefits of each product.
| Info | Details |
|---|---|
| Volume | 20g |
| Key Ingredients | Pure Vitamin C 23%, Super Vitamin E, Glutathione, Adenosine, Niacinamide(B3), Allantoin, Panthenol(B5), Hyaluronic Acid |
| Clinically Proven | Yes (Non comedogenic Test, Sensitive skin irritation test, Primary skin irritation test) |
| Expiration | 24 months from the date of manufacture or 2 months after opening |
| Allergens | Hypoallergenic tested |
| Feature | Vitamin C 23 Serum | Typical Vitamin C Serum |
|---|---|---|
| Vitamin C strength | 23% pure vitamin C + Super Vitamin E + Glutathione | Lower % or less potent formula |
| Target concerns | Brightening dull skin, reducing wrinkles, improving elasticity | Only address one or two concerns |
| Texture / layering | Layers of oil + serum, smooth finish | Heavier or single phase |
| Usage caution / suitability | Requires care (storage, usage) due to high potency | More everyday/basic formula |
Clinically formulated to deliver higher potency, improved elasticity, and multi-layer hydration beyond standard Vitamin C serums. Tested by P&K Skin Research Center Co., Ltd and Dermacosmetic Skin Science Laboratory (Korea).
Based on a 4-week clinical study conducted by Dermacosmetic Skin Science Lab, Korea.
improvement in radiance & brightening
improvement in skin texture
reduction in redness
decrease in pigmentation area
increase in skin elasticity
All clinical studies were conducted by Dermacosmetic Skin Science Laboratory(Korea) from May 3 to June 30, 2025, on 20 adult participants.
Perfect for those already familiar with Vitamin C who want upgrade to a high potency formula for faster and more visible results.
Ideal for dull, tired, or uneven skin, targeting lack of lack of radiance and uneven tone to reveal a brighter, more refined complexion with every use.
Best for those concerned with early signs of aging, including fine lines, loss of elasticity, and rough texture.
Ideal as a targeted solution for dark spots, pigmentation, or stubborn blemish marks that need powerful yet gentle care.
Limited-Time Offer
COSRX Advanced The Vitamin C 23 Serum is formulated with a powerful antioxidant network featuring 23% pure Vitamin C, Super Vitamin E (Tocotrienol), and Glutathione. Based on research, this blend helps stabilize inherently unstable pure Vitamin C, allowing it to be delivered gently and effectively to the skin, making it more comfortable to use compared to many traditional Vitamin C serums.
COSRX Advanced The Vitamin C 23 Serum combines 23% pure Vitamin C with Super Vitamin E and Glutathione for powerful antioxidant care. This high-strength formula stays fresh, absorbs smoothly, and delivers visible brightening and texture improvement without irritation even for sensitive skin.
Yes. Clinical testing showed a 38% reduction in pore volume and over 92% improvement in skin texture after consistent use. This pure Vitamin C 23% serum helps resurface dull areas, reduce the appearance pores, and leave skin smoother and more even-looking.
Most users notice improved brightness and smoother texture within two weeks, with visibly clearer, firmer, and more even-toned skin after four weeks of consistent use. Clinical trials confirmed measurable improvements in pigmentation, pore appearance, and elasticity during this period.
Yes. The formula is non-comedogenic and irritation-tested to ensure it works gently on all skin types. The dual-layer structure combines antioxidant power with soothing hydration from Panthenol and Allantoin, helping repair the skin barrier while minimizing redness or stinging.
Vitamin C helps support collagen, while Adenosine boosts this effect for enhanced resilience. Clinical data showed, during this test period, about a 15% improvement in skin elasticity and a reduction in the appearance of wrinkle depth, promoting a smoother, more lifted look with continued use.
Keep the serum refrigerated between 3–10°C to maintain freshness. Replace the cap with the provided dropper after opening, shake lightly, and apply a few drops to clean, toned skin. Gently pat until absorbed and follow with moisturizer and SPF during the day.
Overall rating: 4.2531204 / 5 from 2003 reviews.
COSRX's Advanced The Vitamin C 23 Serum offers a high concentration of pure vitamin C, praised for its brightening effects and smooth texture. While many customers report positive results and a radiant appearance, some have noted irritation and dryness. The product absorbs quickly and is generally well-received for its hydrating and moisturizing properties.
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"I have used other Serum Vitamin C brands, when I first put this in a little goes a long way. My skin felt refreshed and hydrated. I’ve noticed my dark spots are somewhat lighter. My granddaughters remarked on how my skin glows. Truly a great and worthwhile product that definitely won’t break the bank. l"
"Use it every morning in my routine. I pair it with the alpha arbutin serum and it has made great results by evening out my skintone and lessing acne spots and scars. The serum feels great on my skin and not sticky at all. I suggest pairing it with the alpha arbutin serum for maximizing results of evening the skintone."
"My holy grail of a vitamin C it’s lite but powerful this is a staple in my skincare routine!!! The packaging is cute as well!!"
"After using consistently I have started to notice my skin looking brighter and more even, and it gives me a really nice, natural glow without feeling heavy or greasy. Overall, this has been a great addition to my routine, and I definitely recommend it to anyone who has sensitive skin but still wants the benefits of Vitamin C."
"Love this serum. It's just a little greasy feeling."
"Best Vitamin C serum of all! I’ve tried different brands before but this is by far the best!"
"Loving this! Repurchased. Helping with skin eveness and fading dark spots"
"Works well evens out my skin"
"So far I love this product. My skin glows. At 40 everyone says I look 30. This is before they find out my age."
"This is the 3rd time I buy this serum! Does it smell like cat food? YES… does it oxidize rather quickly unless it kept in the fridge? Also yes, very annoying. And yet I continue to buy, because it works that well on my skin."
