coal-tar preparations (Neutrogena
T/
Gel, Tegrin) ; Pyrithione zinc (Suave
Dandruff Control, Pert Plus
Dandruff Control, Head & Shoulders) ; Salicylic acid and sulfur (T-Sal, lonil T, Sebulex) ; Selenium sulfide (Selsun, Exsel); and Ketoconazole (Nizoral A-D). (ref: http://www.webmd.com/skin-problems-and-treatments/understanding-dandruff-treatment)If these do not help, you may need stronger prescription shampoo from your doctor.
Take care and regards.