COSRX The Vitamin C 13 Serum 20ml

Water, Ascorbic Acid, Butylene Glycol, Glycerin, Sodium Hydroxide, Sodium Hyaluronate, Panthenol, Tocopherol, Allantoin, 1,2-Hexanediol, Ethylhexylglycerin, Sodium Metabisulfite, Disodium EDTA

Apply 2-3 drops to clean, dry skin in the morning, followed by moisturizer and sunscreen. Store in a cool, dark place.

Q: Why does vitamin C serum sometimes change color? A: Pure ascorbic acid (vitamin C) can oxidize when exposed to air, light, and heat, causing it to turn yellow or brown. This is why the serum is packaged in a dark bottle and should be stored properly. Q: Is 13% vitamin C an effective concentration? A: Yes, 13% is an effective concentration for visible results without excessive irritation. Research shows vitamin C is effective at concentrations between 8-20%, with diminishing returns and increased irritation potential above 20%. Q: How long does it take to see results? A: Most users notice brighter, more even-toned skin within 2-4 weeks of consistent use. More significant improvements in hyperpigmentation and fine lines typically become visible after 8-12 weeks. Q: Can I use this with niacinamide? A: Yes, contrary to older theories, current research indicates that vitamin C and niacinamide can be used together effectively. If concerned, you can use vitamin C in the morning and niacinamide in the evening. Q: Does this cause tingling or stinging? A: Mild tingling is normal when first applying vitamin C, especially for sensitive skin or when new to vitamin C. This usually subsides as skin adapts. However, intense stinging or burning indicates irritation, and you should reduce frequency or concentration.