Lack of vitamins will lead to chapping from the corners of the mouth. You should supplement more vitamins, eat more fruits and vegetables, and avoid partial eclipse.
Talking too much or lacking moisture will lead to dry mouth and dry lips, which will accumulate waste skin on lips or corners of the mouth. Usually drink more boiled water, avoid spicy food, eat less roasted seeds and nuts, and eat more vegetables and fruits.
Suggestion: You can take Huanglian Shangqing Pill when necessary, and use anti-inflammatory drugs such as cephalosporin in severe cases.