Mouth ulcers may be related to improper living habits, lack of vitamins, endocrine changes and digestive system diseases. 1. Improper living habits: If the patient usually has irregular living habits and often eats some spicy and stimulating foods, it may lead to the symptoms of mouth ulcers. 2. Lack of vitamins: if the patient usually picky about food or dieting, may make the body lack of vitamin B, vitamin C or folic acid and other trace elements, lowering the body’s immunity, the symptoms of mouth ulcers will always occur. 3. Endocrine changes: mouth ulcers may be related to endocrine changes, for example, during menstruation, the amount of estrogen in the body decreases, which will trigger the recurrence of ulcers. 4. Digestive system diseases: If the digestive system suffers from gastric ulcers, duodenal ulcers and other diseases, it can not efficiently digest and absorb food nutrients, which will easily lead to the occurrence of mouth ulcers. Mouth always ulcers may also be caused by other reasons, it is recommended that patients go to the hospital, under the guidance of the doctor for targeted treatment.