What is COSRX AC Collection Blemish Spot Clearing Serum? COSRX AC collection blemish spot clearing serum has been packed with active ingredients that work together to strengthen sensitive skin and protect it from external irritants. Some of the key ingredients include Propolis Extract, NMF, and the CentellAC-RX complex, which provide moisturizing and calming benefits. Additionally, 4% Niacinamide helps brighten the skin, while EGF offers regenerative care, reinforcing the skin barrier weakened by acne. Ceramide, known for its moisture-retaining properties, works in tandem with NMF to create a smooth complexion. The AC Collection line is specifically designed for acne-prone skin, including hormonal acne.