Biting your lips is a bad habit, and biting your lips may be caused by some kind of pathology. First, lip biting, especially in children, may be tension and anxiety. Second, the lip biting action occurs because of insufficient rest and the nerves cannot control the muscles normally for regular chewing activities. Third, it may be due to fire, swollen teeth and lips, and easy to bite the lips. Fourth, consider whether the lip biting phenomenon is caused by the lack of certain trace elements. If it is a micronutrient deficiency, go to the hospital for examination, check the micronutrients, which micronutrients are lacking, and add which micronutrients, the symptoms can be relieved.