The common causes of nail gnawing in children include lead poisoning, iron deficiency anemia and psychological factors. 1. Children with lead poisoning or excessive lead may cause some damage to the brain nerves, strange behavior, nail chewing phenomenon. 2. Iron deficiency anemia can cause mental behavioral abnormalities, such as irritability, irritability, etc., as well as xenophagia and nail gnawing. 3. Certain psychological factors, such as children in the tension, anxiety, in order to seek psychological comfort, there will be gnawing nails phenomenon, in the psychological can relieve tension and pressure. Children gnawing nails is a bad habit, the nails may contain some bacteria, viruses, harmful to the child’s body, parents should stop in time, pay attention to diligent hand washing, hygiene, develop good habits, abandon bad habits. Children chewing nails may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.