The hair cycle normally consists of growing, resting and falling hairs and there is a delicate balance between these stages of hair cycle. Normally hair should regrow but if it is not happening, you should consider seeing a dematologist.
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I think you are on correct medications for dandruff, Do it daily for 2 weeks and then gradually decrease the frequency. It should work. Remember to keep the shampoo on the scalp for atleast 5 minutes.