Breathing through the mouth for a long period of time can lead to changes in their facial features such as a short, thick, and arched upper lip and a sagging mandible. If you breathe through your mouth for a long period of time, it will cause your face to change such as short and thick upper lip, sagging jaw, misaligned teeth, disappearing nasolabial folds, poor dental occlusion, protruding upper incisors, etc., which is often called “adenoidal facial features”, mainly due to the fact that when you breathe through your mouth, the exhalation of the airflow will produce thrust on the upper jaw, which will seriously affect the beauty of your face. The main reason is that when you breathe through your mouth, the exhaled airflow will push against the upper jaw, which will seriously affect the beauty of your face. Therefore, you should avoid breathing through the mouth, consciously control breathing through the nose, and go to a regular hospital in a timely manner to clarify the cause of breathing through the mouth, and under the guidance of the doctor to carry out an examination and, if necessary, to carry out the appropriate treatment.