There are many causes of mouth ulcers, such as vitamin deficiencies, psychological factors, medications, poor nutrition or changes in hormone levels in the body. If a mouth ulcer occurs repeatedly before menstruation, it is mainly considered to be related to hormone levels and mental factors. It is recommended to adjust your mind and ensure sufficient sleep. Pay attention to a light diet, eat more fresh vegetables and fruits with high vitamin content, and avoid spicy and stimulating foods. If the pain of mouth ulcers is obvious or persistently not relieved, then it is recommended to use B complex vitamins or drugs that promote ulcer healing under the guidance of a doctor. In addition, mouth ulcers are also seen in patients with anemia. Recurrent ulcers can also occur due to heavy bleeding during menstruation and low immunity. It is recommended to do blood tests to clarify the cause and then treat the symptoms in order to cure completely.