Mouth sores (oral ulcers) are one of the most common diseases of the oral mucosa, occurring more often between the ages of 10 and 20, and can occur in both men and women, old and young, and are more common in women. The etiology is still unclear and is related to the immune status of the organism, psychosomatic stress, genetic factors, micronutrient vitamin deficiency, local microcirculation, poor digestion, endocrine, and fatigue. As can be seen, it is difficult to specify a specific cause, and the first three factors are more associated. Characteristics: Periodic recurrence, self-healing, can occur in any part of the oral mucosa, with the lips, cheeks, and tongue edge, ulcers are self-limiting and heal in about 10 days. Recurring or recurrent mouth sores are also known as aphthous ulcers. They are divided into light, heavy and stomatitis types. The mild type is the most common, accounting for 70% of the cases, and is mainly characterized by painful, small ulcers, generally 2-4 mm in diameter, 1-5 in number, with congested edges and yellowish-white pseudomembranes on the surface. Treatment: mainly symptomatic treatment, the purpose is mainly to reduce pain, shorten the duration of the disease and reduce the number of recurrence, but can not completely eradicate recurrence. Local treatment is the application of drugs to achieve anti-inflammatory, pain relief and promote healing, you can choose iodine glycerin, lysozyme containing tablets, Italian can paste, etc.; systemic treatment choose immunomodulatory drugs, including enhancers and inhibitors Prevention: usually should pay attention to keep the oral cavity clean, quit smoking and alcohol, regular life, to ensure adequate sleep; less spicy and stimulating food; women should pay attention to rest before and after menstruation Keep a happy mood and avoid excessive fatigue. Note: Long-term ulcers in the oral cavity may become cancerous, and some chronic traumatic ulcers are often seen to be transformed into oral cancer. For example, when there are unextracted residual tooth roots or unqualified dentures with sharp edges, the sharp edges keep stimulating and scraping the tongue and buccal mucosa to produce ulcers, if the stimulating factors are not removed, the ulcers will gradually aggravate and persist for a long time, which will easily develop into tongue or buccal cancer. Therefore, if the same mouth ulcer persists for more than one month, you should pay attention to the above-mentioned problems and go to hospital to exclude other lesions, so as not to delay the time of treatment.