Children’s upper lip suddenly swollen, common causes are angioneurotic edema, chronic lipitis, gingivitis, trauma and so on. 1. Angioneurotic edema: an allergic reaction confined to the skin and subcutaneous tissues, usually caused by food allergies, insect bites or drug allergies, usually temporary, limited and painless subcutaneous edema. 2. Chronic Lipitis: Lips are swollen, dark red, dry, even flaky, cracked, itchy, dry, and in severe cases, pus secretions. Winter and spring, recurring, with the dry weather in winter and spring. 3. Gingivitis: when gingivitis or oral ulcers, bacterial infection in the mouth can cause swelling of the upper lip. 4. Trauma: children accidentally bite the upper lip when eating food, or trauma bump, can also lead to swelling of the upper lip. Children’s upper lip suddenly swollen, there may be 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.