Frequent mouth ulcers in infants and young children are mainly caused by the following reasons: First, poor oral hygiene in infants and young children. In this case, infants and young children should rinse their mouths with water after each meal or drink milk, and parents should supervise their children to brush their teeth carefully if they have milk teeth growing in their mouths. If the child is too young, parents can use gauze to wipe the surface of the child’s teeth. Secondly, it is caused by the lack of vitamin C, vitamin B or other vitamins and trace elements in the infant’s body. Thirdly, infants suffer from fungal stomatitis in the mouth, due to the infection of Candida albicans, resulting in redness and swelling of the mucous membrane in the mouth of infants, ulcers, in this case parents can use 2% sodium bicarbonate solution for infants to rinse their mouth, you can also dissolve mycophenolate tablets in water for infants to rinse their mouth, and to keep the oral hygiene environment of infants clean.