What is niacinamide and what does it do for skin?

Niacinamide is a water-soluble form of vitamin B3 (also called nicotinamide) and a versatile ingredient that supports the look of a healthy skin barrier, a more even-looking tone, and calmer, less red-looking skin. It acts as a building block for the coenzymes the skin uses for everyday renewal: it can encourage the skin's own production of ceramides and surface lipids (so skin feels more comfortable and loses less water) and may help even out tone by slowing the handoff of pigment packets to surface cells, rather than blocking pigment directly. It is generally well tolerated across skin types, though people who flush easily may prefer to start with a lower strength. The concentration that matters is in the app.