Niacinamide is a form of vitamin B. It has over 40 different functions in the body, 30 are involved in the skin. It thickens the dermis by increasing ceramides, and repairing the barrier lipids that produce collagen and elastin. The percentages used in skincare, range from 2-5% (above 10% will likely trigger irritations). Results of a healthier lipid barrier using 2% niacinamide can be seen within 1-2 weeks. 5% helps lighten trouble spots and can take up to 12 weeks.