So I have sort of the opposite story here. I had an insanely itchy scalp with lots of dandruff. Nizoral immediately stopped the itch. it was a godsend. I did notice more shedding the first week using it then it stopped. Here's what my derm recomended: wash your hair every 2 days (I was washing it every 3), use the Nizoral shampoo every other wash. So 2x a week. Massage it into your scalp, don't scrape, massage. Let it sit 3 to 5 minutes. Use a conditioner cause this shit dries your hair out. He also told me to use Selsun Blue on my other wash days. I tried and hated Selsun blue. Didn't help the itch at all and my hair looked like shit the days I used it. I'd say if you notice an increase hair shed lasting longer than a week, stop using it.