There are many reasons for children’s sudden nosebleeds, which may be caused by environmental factors such as dry weather or rhinitis. 1. Environmental factors: with the change of weather, children’s nasal mucosa will also become dry and will lose the protective effect of the mucosa. If children pick their noses, it will be easy to damage the nasal mucosa, resulting in nosebleeds. 2. Rhinitis: When children suffer from rhinitis due to pathogenic bacterial infection or allergy, the nasal mucosa becomes congested and easily ruptured, resulting in nosebleeds. And rhinitis, the nose itchy, uncomfortable, children with fingers picking the nose, stimulating the nasal mucosa, secondary nose bleeding. There may be other reasons for children’s nosebleeds, so they should go to a children’s hospital immediately for examination and treatment under the guidance of a doctor.