Just after washing your head there are large pieces of dandruff, according to the cause of its onset of treatment. There are three common causes: 1, psoriasis: psoriasis lesions can occur in the scalp, manifested as skin erythema, erythema with large scales, simple shampoo cream can not be eliminated, the treatment can be treated with pyrithione zinc aerosol; 2, ringworm: ringworm belongs to the fungal infections, even after washing your hair, there will be a large piece of dandruff, you can take oral antifungal medication and topical antifungal ointment for treatment; 3, scalp chaff rash : Sometimes it is difficult to clean with ordinary shampoo, treatment can be used compound ketoconazole lotion or Hillson shampoo to wash your hair.