Nioxin Night Density Rescue Hair Thickening Serum - overnight leave-in treatment, clinically proven to boost hair density in 2 months**. This hair serum has a powerful blend of antioxidants known to neutralize free radicals on the scalp surface. Recommended for the first signs of hair loss and is suitable for all hair types.90% of consumers noticed their hair looking healthy*. *Based on clinical study of 60 Italian panelists conducted for 4 months by Eurofins Consumer Product Testing Italy 2018/ 2019.** via antioxidant effect on the scalp surface. Nioxin is the N°1 Salon Brand for thicker and fuller hair with more than 30 years expertise in thinning hair.