Mouth ulcers can be caused by a variety of factors, such as vitamin deficiencies, psychiatric factors, medications, nutritional deficiencies, or changes in hormone levels in the body. Repeated mouth ulcers before menstruation are mainly considered to be related to hormone levels and mental factors. It is recommended to adjust your mindset and get enough sleep. Pay attention to a light diet, eat more fresh vegetables and fruits with high vitamin content, and avoid spicy and stimulating food. If the pain of mouth ulcers is obvious or persistently unrelieved, it is recommended to use B-complex vitamins or drugs to promote ulcer healing under the guidance of a doctor. In addition, mouth ulcers are also seen in patients with anemia. Due to heavy bleeding during menstruation, low immunity can also cause recurrent ulcers. It is recommended to do routine blood tests to clarify the cause of the disease and then treat the symptoms in order to cure it completely.