Our 4-in-1 nicotinamide serum contains vitamin C and Vitamin E. It can soothe sensitivity, reduce redness, enhance skin resistance, promote skin circulation, and speed up metabolism. Its use method is very simple: clean the facial skin, keep dry, take a proper amount of essence, evenly apply to the facial skin. Massage gently with your hands to promote absorption. It also strongly locks in water molecules, keeping the skin hydrated.