Niacinamide is a tongue-twisting, hard-to-pronounce skincare ingredient that you might not be familiar with, but in reality it's been a staple in dermatologists' offices for years. The multitasking ingredient is the other name for vitamin B3. In medical circles it's known for being extremely effective for treating acne, redness, hyperpigmentation, and signs of aging, plus its compatibility with all skin types.