COSRX The Vitamin C 23 Serum is a potent, water-free 23% L-Ascorbic Acid serum formulated to target hyperpigmentation, uneven tone, and dullness effectively.

What It Is

This is a high-concentration L-Ascorbic Acid serum, a notable departure from COSRX's usual gentle, barrier-focused offerings. It directly addresses photodamage, post-inflammatory hyperpigmentation (PIH), and overall skin luminosity. Unlike many other Korean Vitamin C serums that use derivatives or lower percentages, this one directly competes with formulas like Paula's Choice C15 Super Booster or Timeless 20% Vitamin C. It is for those who have tried gentler options and are ready for significant brightening results.

Key Ingredients

• L-Ascorbic Acid (23%): A pure form of Vitamin C, it functions as a powerful antioxidant, inhibiting melanin production to brighten skin, stimulate collagen synthesis, and neutralize free radicals from UV exposure.
• Tocopherol (Vitamin E): A fat-soluble antioxidant that synergistically boosts L-Ascorbic Acid's stability and efficacy, protecting cells from oxidative damage and providing barrier support.
• Sodium Hyaluronate: A form of hyaluronic acid, it attracts and holds moisture in the skin, providing hydration without heaviness, which helps mitigate potential dryness from LAA.
• Allantoin: Known for its soothing properties, it helps to calm irritation and support skin regeneration, making the high concentration of LAA more tolerable for some users.

This serum's strength lies in its focused, minimalist approach to brightening, prioritizing a high percentage of L-Ascorbic Acid. The formula is water-free to maintain LAA stability. It notably omits potential irritants like fragrance and essential oils, opting for a clean, effective delivery. The pH would typically be acidic, around 2.5-3.5, for LAA efficacy.

Who It's For

How To Use

1. When in routine: After cleansing and toning, before heavier serums or moisturizers, AM or PM.
2. How much: 2-3 drops.
3. How to apply: Gently press onto the face, avoiding the eye area.
4. What to layer next: A hydrating, soothing serum or a barrier-repairing moisturizer.
5. Frequency: Start 2-3 times per week, gradually increasing to once daily if tolerated. Always use SPF in the AM.

Frequently Asked Questions

Does 23% Vitamin C sting or tingle on application?

Yes, a mild tingling sensation is common, especially during initial use. This is due to the low pH of L-Ascorbic Acid and usually subsides as skin adjusts. If stinging is severe or prolonged, discontinue use.

Can I use this serum with other actives like retinoids or AHAs?

It is generally not recommended to use this high-concentration Vitamin C serum at the same time as retinoids (retinol, retinal) or strong AHA/BHA exfoliants. Alternate days or use Vitamin C in the morning and other actives in the evening.

How do I prevent the serum from oxidizing?

Store the serum in a cool, dark place, ideally refrigerated. Ensure the cap is tightly sealed after each use. The dark glass bottle helps, but L-Ascorbic Acid is prone to oxidation, indicated by a dark orange or brown color change.

Will this serum cause purging or breakouts?

While L-Ascorbic Acid does not typically cause purging in the way retinoids or AHAs might, some individuals may experience initial irritation or minor breakouts as their skin adjusts to the potency. Start slowly to minimize this.

Pairs Well With

To support the efficacy and mitigate potential irritation of COSRX The Vitamin C 23 Serum, pair it with hydrating and barrier-fortifying products. A ceramide-rich moisturizer will help seal in moisture and repair the skin barrier. Incorporate a soothing toner, like one with Centella Asiatica or Mugwort, to calm any redness. During the day, a broad-spectrum SPF 30+ is non-negotiable to protect the skin and maximize the Vitamin C's antioxidant benefits.