Facial serums do much more than moisturize the skin. Antioxidants are essential to halt the signs of aging. After cleansing and toning, the skin's natural sebum levels need to be replaced, protecting the skin against environmental toxins. The skin's natural moisturizing factors need to be replenished and the barrier function needs to be restored. Nikua Skin's moisturizing serums are packed with functional, active ingredients. Take care to store serums in a cool location to prolong shelf-life. Start with a drop or two of serum to cover face and neck. A thin layer of serum will absorb quickly and last all day.