4-year-old female baby suddenly dandruff on the back of the head, may be caused by normal physiological phenomena, seborrheic dermatitis, ringworm and other factors. It is recommended to wash the hair frequently, can also be given glucocorticoids, antifungal drugs topical application, can help improve. 1. Physiological phenomenon: small children suddenly have dandruff on the head, if less, considered a normal phenomenon, is the result of cell metabolism. It is recommended to pay attention to clean, generally do not need to use drugs to treat. 2. Seborrheic dermatitis: Seborrheic dermatitis can occur in the seborrheic parts, can also occur in the scalp, may cause dandruff. Tacrolimus and pimecrolimus ointment can be given for external application. If secondary bacterial infection occurs, it can be treated with medication such as fusidic acid cream. 3. Tinea capitis: Tinea capitis is caused by fungal infection, which may lead to dandruff, hair loss and other symptoms on the head. You can take itraconazole capsules and terbinafine hydrochloride tablets orally, and use ketoconazole, econazole and miconazole topically to kill or inhibit the fungus. Dandruff on the head of a 4-year-old baby, it is recommended to go to the dermatology department of the hospital in a timely manner, under the guidance of the doctor to give the appropriate drug treatment.