Mouth ulcers are not always caused by vitamin deficiency. The lack of vitamins is one of the causes of mouth ulcers, in addition to genetic, immune, mental, sleep disorders, traumatic factors, dietary habits, changes in hormone levels, systemic diseases and many other reasons. 1, genetic factors: mouth ulcers have a genetic tendency, parents with recurrent mouth ulcers, the chances of children suffering from mouth ulcers will increase; 2, immune factors: low autoimmunity For an important factor that induces mouth ulcers. Immunity decreases when the body is susceptible to pathogenic attack, and the immune response process consumes the body immune protein, accelerating the occurrence of mouth ulcers; 3, mental factors: under the heavy pressure of life, work, easy to appear mental tension, anxiety and depression, irritability and other bad emotions, which in the long run can easily trigger mouth ulcers; 4, sleep disorders: if long-term insomnia or sleep disorders will lead to environmental disorders in the body, immunity 5, traumatic factors: physical damage is the most common, their own teeth bite, wearing braces, toothbrush scratches, etc. are easy to damage the oral mucosa caused by mouth ulcers; 6, dietary habits: oral mucosa is weak, eating hard food is easy to scratch or wear mucosa, eating too hot food is easy to cause mucosa rupture erosion thus leading to the occurrence of mouth ulcers; 7, hormone level Changes: If the progesterone content is low before women’s periods, the oral mucosa is prone to ulcers; 8. Systemic disease factors: Patients suffering from systemic diseases mainly induce mouth ulcers by affecting immune system disorders, such as gastrointestinal ulcers, gastritis, hepatitis and other diseases. Patients with recurrent mouth ulcers should be seen in hospital in time for early examination and early diagnosis and standardized treatment. Daily should also pay attention to diet, eat more fresh fruits and vegetables, avoid picky eating; avoid staying up late, ensure sufficient sleep, etc.