The causes of recurrent low-grade fever in infants and young children are: 1. Infections, common upper respiratory tract infections, intracranial infections and systemic infections in infants and young children may show symptoms of recurrent low-grade fever. Because the immunity of infants and young children is lower than that of adults, they are very vulnerable to viruses and bacteria, etc. Recurrent low-grade fever can occur after chronic inflammation, as well as infections with tuberculosis or other bacterial infections that can spread to various organs throughout the body, resulting in recurrent low-grade fever. There are also many infants and toddlers who can develop systemic symptoms such as recurrent low-grade fever due to urinary tract infections. if the infection is not controlled, the infant may progress from persistent low-grade fever to high fever convulsions, etc. 2. infants and toddlers with insufficient water intake, excessive water metabolism, and dehydration can also develop recurrent low-grade fever and need timely correction of dehydration. 3. external environmental factors, including high indoor temperature and children wearing too thick clothes, can The situation of hypothermia can occur.