Hello! Rotten corners of the mouth are medically called "angular stomatitis", which is mostly due to the lack of vitamin B2 in the body. Due to different causes, angular stomatitis can be divided into nutritional angular stomatitis, bacterial angular stomatitis and fungal angular stomatitis, among which nutritional angular stomatitis is the most common. Therefore, the prevention of "angular stomatitis" should start from the following points. 1, pay attention to adjusting diet and not being partial to food. Appropriately increase foods rich in B vitamins, such as bean products, eggs, lean meat and animal liver, to prevent riboflavin deficiency. 2. Pay attention to the cleanliness and moisturizing of the face. Wash your face in time after meals and dry your mouth. When the weather is cold and dry, you should always apply some moisturizer locally. When the lips are dry and peeling, you can apply anti-cracking oil, such as vaseline, cod liver oil or oily skin cream, but you must never apply glycerin, because glycerin is not oil, it has dehydration effect and will dry the skin. 3. Getting into the habit of drinking boiled water often will help improve the body's and skin's moisturizing degree. If you wait for dry mouth to drink water, it will lead to water shortage in the body. And correct the bad habit of licking the corners of the mouth frequently. In case of angular stomatitis and chapped bleeding, the wound should be washed with warm water or salt water first, and then applied with antibiotic ointment, such as chlortetracycline eye ointment or cod liver oil riboflavin paste, and taken orally. When the wound starts to scab, don't tear off the scab forcibly, and let it fall off after self-healing. At the same time, vitamin B2 and vitamin C can be taken, and chlortetracycline ointment can be used for external application.