I never noticed any damage when I used my diffuser, but I don't use it often at all. When I do use it, I do this thing where I dry an area of my hair, point the dryer away from my head, move it to the next area, and redirect the dryer back to my head. I never let it just blow my hair all over the place. Otherwise, I get frizzy hair. Heh, I hope that made sense.