There are many causes of mouth sores, which are broadly summarized in the following types: 1. mental factors, patients are most prone to mouth sores when they are mentally stressed, have high mood swings, and do not get enough sleep. 2. it may be due to vitamin and micronutrient deficiencies, such as vitamin B, vitamin C, and folic acid, iron, zinc, etc., and these micronutrients The lack of these micronutrients will lead to malnutrition and low immunity, which will increase the possibility of mouth sores and mouth ulcers. 3, may also be related to endocrine changes, some women are prone to mouth ulcers during menstruation, which is caused by changes in the level of progesterone in the body.