The etiology of recurrent mouth ulcers is unclear and may be related to several causes. Recurrent oral ulcers are a common oral mucosal disease, also known as recurrent oral ulcers, where mucosal lesions recur within the oral mucosa or recur in one location. The common cause is the result of low immunity. Lack of vitamins or trace elements in the body, especially vitamin B and vitamin C. Iron deficiency can also lead to increased brittleness of the mucosa, and mouth ulcers can easily appear if the mucosa is accidentally bitten. You can usually eat more vegetables and fruits to replenish vitamins and strengthen physical exercise to improve your immune system. Mouth ulcers are also related to genetic factors, parents with good mouth ulcers, children have a higher chance of developing mouth ulcers. It is also related to mental tension or gastrointestinal indigestion. Frequent constipation or fatigue, as well as age-related menopause, are associated with recurrent ulcers. Mouth ulcers tend to develop when the immune system is low, such as sleepless nights or dry stools and colds and fevers. Recurrent mouth ulcers are also associated with bacterial infections, or reactions to systemic diseases in the mouth, such as leukoaraiosis, or local trauma. Therefore, recurrent mouth ulcers may be related to immune deficiency, vitamin and trace element deficiency, genetic factors or local trauma, or may be a manifestation of a systemic disease in the mouth.