The basic cause of thrush is a decrease in immunity and over proliferation of Candida, which is common in infants and young children. It is often triggered by high-risk factors such as long-term hormone users, HIV-infected patients, immunodeficiency patients, etc. 1. Low immunity. Infants and young children, the elderly, HIV-infected people, long-term use of glucocorticoids and other immunosuppressants will cause low immunity, Candida overproliferation, the disease can occur. 2. High risk factors. Mothers with Candida albicans infection, easily transmitted to newborns during labor, bottles, pacifiers, mothers with unclean breasts, bad habits such as biting fingers, clothes, etc., can induce pediatric disease. Long-term use of broad-spectrum antibiotics in large quantities may cause flora disorders, or may induce the disease. The specific cause of thrush has to be examined and diagnosed by a doctor.