I Tested 5 Korean Vitamin C Serums for Hyperpigmentation — Only These Work in 2026
Tested 5 Korean vitamin C serums for six weeks on real hyperpigmentation: COSRX at 23% L-ascorbic acid leads for stubborn dark spots, Klairs is the safest entry for sensitive skin, and Goodal delivers the best value for daily brightening. Full rankings, an honest pros-and-cons breakdown, and a comparison table by skin type inside.