There are many reasons for nosebleeds, mainly related to nasal mucous membrane damage, blood vessel rupture, dry environment, rhinitis, nasal polyps, nasal tumor and trauma. 1. Dry environment: dry air, lack of moisture in the nasal mucosa, which can easily cause the mucosal capillaries to rupture and cause bleeding. 2. Rhinitis: mainly acute upper respiratory tract infection or rhinitis and other causes of mucosal thickening, edema, prolonged stimulation is easy to capillary expansion, rupture caused by bleeding. 3. Nasal polyps: chronic inflammatory stimulation will lead to epithelial cells, vascular tissue proliferation into polyps, bleeding necrotic polyps will make bleeding nose. 4. Nasal tumor: Nasal tumor itself has active proliferation of tissue cells, poor blood supply ability, brittle texture, which can easily cause mucosal rupture and bleeding. 5. Trauma: Violent factors lead to blood vessel rupture and cause bleeding. When repeated nosebleeds can not be relieved, it is necessary to pay attention to it, and consult a doctor in time for a clear diagnosis.