COSRX The Niacinamide 15it suggests a serum containing a 15% concentration of niacinamide as its main active ingredient. Niacinamide, also known as vitamin B3, is a popular and well researched skincare ingredient with various benefits for the skin. Here are some potential benefits of niacinamide in skincare products: Regulation of Sebum Production: Niacinamide can help regulate sebum production, making it beneficial for those with oily or acne prone skin. it suggests a serum