Dandruff is a big piece of dandruff, considering that it is caused by ringworm of the head, seborrheic dermatitis of the scalp and other diseases. 1. Tinea capitis: If the head is infected with rust-colored microsporidium, canine microsporidium and other fungi, it is easy to induce tinea capitis, so that the patient appears hair loss, dandruff is very large, scalp itching and other symptoms. Tinea capitis is a contagious disease, if the head directly or indirectly contact with the items of tinea capitis patients, may therefore cross infection, induced tinea capitis. 2. Seborrheic dermatitis of the scalp: genetic factors, malassezia infection and other factors are common causes of seborrheic dermatitis of the scalp. Patients may have symptoms such as very large dandruff and oily scalp. Patients with large dandruff are advised to seek medical attention to determine the cause of the problem.