The causes of nosebleeds in infants include dry air, abnormal coagulation function and deviated nasal septum. 1. Dry air: dry air in the fall and winter seasons can cause some stimulation to the infant’s nasal mucosa, leading to capillary rupture and bleeding, resulting in nosebleeds. 2. Abnormal coagulation function: infants suffering from blood diseases, such as thrombocytopenia, coagulation factor deficiency, can occur spontaneous rupture of the nose capillaries bleeding. 3. Nasal septum deviation: Nasal septum deviation will affect the normal flow of airflow through the nose, and may also lead to dryness of the nasal mucosa, which may lead to capillary rupture and bleeding. If a baby’s nose bleeds during sleep for a long period of time, it is recommended that the baby be taken to the ENT department of a hospital, where the cause of the bleeding can be clarified after a complete examination and treated according to the cause of the bleeding.