Babies sleeping with their mouths open may be physiological or pathologically caused, and need to be corrected for different conditions. Can take general treatment, medication and other improvements. 1. Physiological: the baby sleeps with his mouth open may be caused by the habit of breathing with his mouth open and the relaxation of the upper and lower lip and cheek muscles. You can let the baby in the awake state, during the day, practice aerobic exercise shut up breathing, in aerobic exercise, the baby will consciously shut up breathing, after long-term training, can slowly help the baby to develop habits. 2. Pathological: the baby sleep open mouth may be caused by rhinitis and adenoid hyperplasia. (1) allergic rhinitis: this is because rhinitis can lead to the nasal cavity is not ventilated, the baby will be open-mouthed sleep, need to actively give anti-inflammatory aspects of the treatment, generally can be used externally with hormone nasal spray, such as budesonide, mometasone furoate nasal spray, etc., to soothe the symptoms of the nasal cavity above. (2) adenoid hyperplasia: need to go to the ear, nose and throat department for surgical treatment, after removing the local lesions, open-mouth breathing to sleep will generally improve. The baby sleeps with his mouth open, there may be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, give targeted treatment or treatment. All of the above medications should be used under the guidance of a doctor.