Hello....... Dandruff is a common situation more common among teenagers. It can be more problematic if you are using hair oils. So consider discontinuation of oils and using an antifungal shampoo everyday for first week and then reduce the application to twice a week for maintenance. You should keep the shampoo at-least for 5 minutes on the scalp for it to act. Wash hair daily. if problem persists, consult a Dermatologist for proper diagnosis and treatment