Only using for 3 weeks, noticed slight improvement in volume, don't think I am yet qualified to comment fully. Have ordered full size bottles, but on reading reviews of serum think I should now order that. I took a photo of my hair before I started with shampoo and conditioner, will begin with serum when it arrives, and will submit a photo if there is an appreciable difference. I have always had fine hair, plenty at the back but very sparse at top.