COSRX Vitamin C 23 Serum Review: Is It Right for You? (2025)

Overview

Is your skin stuck in a cycle of dullness, uneven tone, or fine lines that seem a little too comfortable hanging around? Finding a product that truly makes a difference is almost impossible.

COSRX Vitamin C 23 Serum claims it could help. Packed with 23% pure vitamin C, this serum claims to brighten, smooth, and tackle stubborn wrinkles while improving elasticity. Its two-layer formula blends antioxidant-rich oils with stabilized vitamin C, aiming to lock in moisture and keep your glow.

Is it the powerhouse it claims to be? Or just another serum on the shelf? Let’s find out.

What is COSRX Vitamin C?

The COSRX Vitamin C 23 Serum is a highly concentrated skincare product designed for anyone looking to enhance their skin’s overall appearance.

This serum focuses on issues like uneven tone, dullness, wrinkles, and skin elasticity. The serum boasts a 23% stabilized pure vitamin C formulation, a feature aimed at delivering noticeable results in improving skin texture and brightness.

The serum claims to combine antioxidant-rich oils and vitamin C to create a balance between hydration and active care. This serum aims to address fine lines and boost radiance.

How Does COSRX Vitamin C Rate According to Our Experts?

About the Manufacturer

COSRX, established in 2013, is a South Korean brand offering skincare solutions in over 146 countries. They are admired for their focus on skin-friendly formulas and innovative research. With 24 teams and 3 research centers, they address various skin concerns with accessible pricing and minimalistic designs.

However, their reliance on specific active ingredients may not suit all skin types. We also noted they have limited product availability in certain regions, which can a problem for international customers.

How Does COSRX Vitamin C Work?

The COSRX Vitamin C 23 Serum claims to deliver a concentrated form of active ingredients directly to the skin. It is designed to target uneven skin tone, dullness, and signs of aging, like fine lines.

The serum claims to penetrate deeply, aiming to brighten and rejuvenate the skin’s appearance over time. Its dual-layer formula combines hydration with active properties to support moisture retention while addressing skin concerns. Regular use is said to help improve skin texture and promote a smoother, more radiant look.

However, due to its high concentration, it should be introduced carefully into routines to minimize irritation.

COSRX Vitamin C Ingredients – Are They Safe & Effective?

Here are the key ingredients and what each brings to the table;

Vitamin C (Ascorbic Acid)

The serum includes 23% pure Vitamin C, or ascorbic acid, a highly stabilized antioxidant. This ingredient is chosen for its ability to brighten the skin, reduce dullness, and target visible signs of aging, such as wrinkles.

It also works on uneven skin tone and hyperpigmentation by supporting melanin reduction, while boosting collagen to enhance elasticity and firmness.

Super Vitamin E (Tocotrienol)

Tocotrienol, aka ‘Super vitamin E’, is known to have more antioxidant activity than tocopherol, the traditional form of vitamin E.

It protects the skin’s structure from environmental stress, stimulates collagen production, and helps delay premature signs of aging like sagging and fine lines. As said in the Peter Thomas Roth Potent-C Power Serum reviews, Ferulic Acid combines well with Vitamin C, significantly improving the skin’s resilience to oxidative damage.

Hyaluronic Acid

Renowned for its ability to retain up to 1,000 times its weight in water, hyaluronic acid is included to provide deep hydration. It helps to counteract dryness often caused by high concentrations of active ingredients.

This ensures the skin remains plump, smooth, and hydrated, promoting a healthier barrier function and improved overall texture.

Allantoin

Allantoin serves as a soothing and reparative agent in the serum. It calms irritation, reduces redness, and supports skin regeneration by aiding the recovery of damaged tissues. Allantoin helps the skin adapt to the potent Vitamin C concentration, ensuring a smoother, gentler experience without compromising efficacy.

How to Use COSRX Vitamin C?

Gently shake the bottle to mix its dual layers. Apply a few drops onto cleansed, dry skin during the serum step, preferably in the evening.

Start with a small amount to test skin tolerance and gradually increase usage if no irritation occurs.

Massage the serum gently, focusing on areas with uneven tone or dullness. If using during the day, follow with sunscreen of SPF 30 or higher.

Always store the serum upright in the refrigerator and use within two months of opening.

Benefits of COSRX Vitamin C

• Brightens Skin Tone: The serum is designed to target dull, uneven skin by helping to reduce hyperpigmentation and dark spots. Its brightening effect aims to restore a radiant, more uniform complexion. If you’re looking for another option with similar benefits, WOWMD Glow Fusion Vitamin C Serum is also known for its ability to enhance skin radiance and even out tone.
• Improves Elasticity: COSRX Vitamin C claims to support collagen production, which may help improve skin firmness and elasticity. By addressing signs of aging like sagging skin, it promotes a smoother appearance.
• Smooths Texture: The serum works to refine skin texture by targeting rough, uneven areas. It aims to leave skin feeling softer and looking more polished over time.
• Hydrates the Skin: With hydrating properties, COSRX Vitamin C is said to help skin retain moisture, reducing dryness often caused by potent actives. This helps maintain a plump and healthy-looking appearance.
• Reduces Wrinkles: COSRX Vitamin C may assist in diminishing the appearance of fine lines and wrinkles. By improving overall elasticity and hydration, it targets common aging concerns for a rejuvenated look.

Side Effects and Safety Of COSRX Vitamin C

Side Effects

Some users have reported experiencing stinging or redness after applying the serum, especially with sensitive skin. Others mentioned an odd smell that may be unpleasant. A few reviews highlighted occasional breakouts or burning on damaged skin, suggesting it may not suit all skin types.

Safety Measures

For safety, COSRX advises storing the serum in the fridge to maintain its potency and reduce oxidation. Begin with a small amount, especially if new to vitamin C products, and avoid application on broken skin. Using sunscreen during the day is strongly recommended when incorporating this product.

COSRX Vitamin C Price

A single bottle of COSRX Vitamin C 23 Serum currently costs $34.99 for a 0.7 oz bottle on Amazon. The COSRX Vitamin C 23% Peptide Booster Set, which includes the Vitamin C Serum and a Peptide Booster Toner, is also offered at $34.99. If you’re exploring other options, check out retailers like Walmart for availability. You get a 30-day money-back guarantee when you purchase from the official website.

COSRX Vitamin C Review – FAQs

Q: Can COSRX Vitamin C 23 Serum be used by individuals with sensitive skin?

A: The serum claims it contains high-concentration Vitamin C, which may irritate sensitive skin. Be sure to perform a patch test before applying it to the face. Start with a small amount and use it less frequently to build tolerance. If irritation persists, reduce usage or stop completely.

Q: Why does COSRX Vitamin C 23 Serum sometimes sting or cause redness?

A: The high concentration of pure Vitamin C (23%) may cause a stinging sensation, especially on broken or sensitive skin. This reaction is common with potent actives. The brand claims pairing the serum with a moisturizer can reduce discomfort.

Q: Does COSRX Vitamin C 23 Serum oxidize quickly, and how can it be stored?

A: Vitamin C serums are prone to oxidation. COSRX tries to combat this with a specialized bottle design. However, it’s advised to store the serum in a refrigerator to maintain freshness and effectiveness.

Q: What products should I avoid mixing with COSRX Vitamin C 23 Serum?

A: Avoid using the serum alongside hydroxy acids like AHA or BHA, as combining them can increase irritation. Stick to simpler routines and avoid layering too many potent actives.

What Do COSRX Vitamin C Reviews Say?

Here are the top comments we singled out;

I used these just as directed. The entire bottles of each. I do not see or feel any change in my skin. It’s definitely not worth the hype. Well maybe if you are in your twenties early thirties. But as for late forties absolutely not. I don’t even give it one star. Sorry but it’s how they worked for me! Okay it made give one star to post my review. –Jennifer Lynn.

Wanted the 6 Peptide serum and at the time it was only available in this bundle. I’ve used other COSRX products, the Peptide serum being my favorite for 56 year old skin. Their Vit C serum however went bad very quickly, so I’ll stick with my usual brand (Timeless) but keep using the peptide serum. I haven’t seen any improvement with my skin with it but it should fill that peptide slot nicely, the serum is a good weight and ingredient line up. Will keep buying. –The Happy Body Channel.

I love how my skin is supple and smooth! This combo is amazing. Great amount of product as well. Fair warning, the vitamin C serum is slightly strong smelling, and is a little more oily. However, it still works like a charm. Would definitely purchase again. –Alexis.

COSRX Vitamin C Review – Conclusion

COSRX Vitamin C 23 Serum targets those looking to refine their skincare routine. Its high concentration of pure Vitamin C suggests potential for brightening, smoothing, and addressing signs of skin aging.

But, you have to know users with sensitive skin may experience stinging or redness, making careful patch-testing essential. Since it easily oxidizes, it requires mindful storage, such as refrigeration, which could feel inconvenient for some.

On the plus side, its fragrance-free composition and compatibility with complementary products like peptide toners offer some flexibility. Whether this serum enhances your routine depends on your skin’s tolerance and commitment to its unique requirements.