Diamax™ is leave-on treatment that can be used with the Nioxin 3-part systems for fuller, thicker looking hair. Nioxin DiamaxTM is an innovative approach to the treatment of fine, thinning hair with a fusion of Niacinamide, Panthenol and Caffeine. Proven to increase the diameter of each existing hair strand, penetrate hair, and make it fuller and more manageable. The serum strengthens hair’s resilience against breakage.