The corners of the mouth repeatedly cracked for the following reasons: First, the lack of vitamins and trace elements in the body, commonly found in people who are picky eaters and partial eaters, due to the lack of B vitamins, vitamin C and vitamin E in the body and iron, zinc and selenium in trace elements, are prone to inflammation of the corners of the mouth and lips, resulting in chapped lips and corners of the mouth, bleeding and erosion. Second, the external environment wind, sun, dry, also easy to induce inflammation of the corners of the mouth, in this case it is recommended to apply lip balm to the corners of the mouth to keep the local moisture, while wearing a mask is recommended before going out. Third, eating spicy, irritating food such as food contact to the corners of the mouth will cause stimulation to the local mucosa, causing the mucosa to bleed and crack.