A piece of white at the corner of the mouth is commonly caused by the following: 1. If the surface is smooth, not painful or itchy, consider the white spot caused by melanin deficiency, rub the affected area with vitamin A acid ointment, take oral multivitamin element tablets, usually eat black beans, black sesame and other foods with high melanin content in moderation, and eat less or no kiwi, orange and other foods with high vitamin C content. 2. At the very beginning the skin at the corner of the mouth area is red and itchy, and after A week or so the red skin gradually become white, the surface is rough, above the white flakes off, the affected area has itching or burning sensation, consider is white pityriasis with vitamin B6 ointment to rub the affected area, oral vitamin B2, vitamin C. 3, patients suffering from perioral inflammation, after the inflammation subsides the affected area skin appears white, due to poor local blood circulation, hypopigmentation caused by gently massaging the affected area with your hand to promote local Blood circulation, use tacrolimus ointment to rub the affected area.