I have been using Nizoral for about a year and DEFINATELY notice more hairs shedding when I use it. When I use normal shampoo (everyday) I don't notice many shed hairs, when I use Nizoral I do notice a lot.
I used to use Nizoral once every 3 days or so, but have recently dropped back to about once every 10 days. Itch is less, flakes are up a little but I think my scalp is healthier for it.
Don't overdo it.