Large dandruff crusts on the scalp, consider the following diseases: 1. Psoriasis vulgaris, in clinical treatment you can spray pyrithione zinc aerosol externally, or apply mometasone furoate cream with zinc oxide ointment borate. You can also choose selenium disulfide lotion to wash your hair three times a week, and you can undergo phototherapy through 308nm excimer laser or medium-wave narrow-spectrum ultraviolet radiation. If the rash is severe, you can take oral Avion capsule for anti-proliferative and anti-inflammatory treatment, or you can choose cyclosporine A soft capsule for immunosuppressive treatment.2. Tinea capsule, which is caused by fungal infection, can be treated with oral itraconazole capsule and topical terbinafine hydrochloride gel or naftifine ketoconazole cream for antifungal treatment.