Yellowing of the corners of the mouth is mostly caused by erosion in the corners of the mouth area, caused by stomatitis. The cause of the disease is mainly due to the lack of vitamins and trace elements in the human body, especially when the lack of B vitamins, vitamin B, vitamin E and trace elements in iron and zinc, are easy to cause repeated ulceration of the corners of the mouth, making the corners of the mouth cracked, red and swollen, when secondary to bacterial infection, the surface of the fissures in the corners of the mouth will be covered with Yellowish-white pseudomembrane. You can apply erythromycin ointment locally to the corners of the mouth for anti-inflammatory purposes, ensure a balanced diet, avoid spicy and irritating foods, drink more water and eat more fresh fruits and vegetables, and don’t always lick the corners of the mouth with your tongue because there are a lot of bacteria on the tongue that can aggravate the local trauma infection at the corners of the mouth. It is also possible that the vesicles are due to a viral infection around the corners of the mouth, causing the corners of the mouth to blister first and then break down and become vesicles, so it is recommended to take anti-viral medication, such as Banlangen granules for treatment.