Frequent mouth ulcers may be caused by low immunity, lack of vitamins, lack of trace elements, or may be related to systemic diseases, such as having diabetes, anemia, gastrointestinal disorders, etc. All these comprehensive symptoms may produce mouth ulcers. In addition, if the oral hygiene condition is poor, there is a large amount of dental calculus, plaque, or have dental caries, it will also often produce the symptoms of oral ulcers. Mouth ulcers are usually self-healing, and light mouth ulcers will heal themselves in 7-10 days; while large mouth ulcers usually take half a month, or even 1-2 months to heal. Frequent mouth ulcers, to regulate systemic diseases, improve the body’s resistance, but also to remove local irritants, to maintain good oral hygiene. The surface of the ulcer can use ulcer paste, stomatitis spray, etc. If the ulcer is deep and large, you can also use prednisolone, tretinoin and other suspensions for local injection to promote the healing of the ulcer.