Ketoconazole: NIZORAL. As my shampoo?

Hello and have a good day to all Doctors who will read this. My concern is about the over-the-counter shampoo Nizoral. I have been using this one since last week due to my severe dandruff. I bought only three sachets to try it out, I find it somehow effective though after the first wash. My scalp is not that itchy anymore unlike before but still, the presence of the flakes are there. I have been alternating the use of this shampoo because there's a direction at the back of the sachet of the shampoo saying "use twice a week for treatment for 2-4 weeks." I am following it though since I only bought three. I used another anti dandruff shampoo when I am not using Nizoral, but my scalp will itch. Is it okay to use Nizoral everyday as my shampoo? I really have a sensitive scalp. Thank you.