If your haircare goals are all about increasing the look of hair density, Nioxin’s Density Defend Diaboost Hair Thickening Serum aims to promote visible hair growth to leave hair looking fuller. Powered by a blend of niacinamide and peppermint oil, the targeted leave-in treatment seeks to protect and nourish, while working from the root to help boost strands with volume. Hair appears stronger and thicker for a fuller-looking finish.