The purple color in the middle of the lower lip of infants is mainly caused by cold, dehydration, hypoxia, myocardial ischemia, etc. It is necessary to go to the hospital for examination to clarify the cause and then treat it symptomatically. Common causes and treatment 1, cold: infants produce less heat, can be caused by cold resulting in poor peripheral circulation, vascular contraction and local skin purple, and the skin at the lips is thin, so it will be more obvious. It is necessary to add clothes, cover quilts, or appropriate amount of hot compresses in time to promote warming. Avoid cold and stimulating food, such as ice cream; 2. Dehydration: Due to factors such as diarrhea or vomiting, resulting in insufficient blood volume and poor peripheral circulation, purple color in the middle of the lips can also appear, accompanied by symptoms such as sunken eye sockets and poor skin elasticity. Under the guidance of professional doctors, electrolytes and other fluids should be replenished to correct dehydration. 3. Hypoxia: Commonly caused by pneumonia and other respiratory diseases, caused by lung infection resulting in insufficient oxygen inhalation or carbon dioxide not being expelled in time. Oxygen inhalation, nebulization, anti-infection treatment, or oral administration of aminobromine hydrochloride oral solution to dilute sputum, and timely removal of oropharyngeal secretions to prevent blockage of the respiratory tract, causing respiratory difficulties; 4, myocardial ischemia: often caused by congenital heart disease such as tetralogy of Fallot, congenital aortic constriction, and can also be caused by anemia. If it is congenital heart disease, surgery is usually required. If it is caused by anemia, it can be treated with iron supplements, folic acid and vitamin B12. Parents are advised to feed their children water regularly to replenish sufficient amount of water daily. It is also necessary to pay attention to the child’s mental state and physical changes, such as crying, depression, etc. If abnormal conditions are found, immediate medical attention is required.