Thrush is a mucosal lesion in the mouth caused by an infection of Candida albicans. Which department to visit depends on the child's age, the specific condition of the disease, and whether there are any underlying diseases. Usually, if it is a newborn, they should visit the neonatology clinic. For infants and young children, it is generally appropriate to visit the pediatric clinic or pediatric emergency department during normal working hours. During non-working hours, which means noon, night, weekends, and holidays, the pediatric emergency department should be visited. Of course, if the child has an underlying disease or is taking immunosuppressants that lead to a decrease in immunity, causing thrush, the department treating the primary disease should be consulted.