There are many reasons for nosebleeds, which can be divided into local and systemic causes, local causes include trauma, nasal foreign bodies, tumors, etc., and systemic causes include acute infectious diseases. Local causes of nosebleeds are: ① trauma, such as nose picking, forceful nose blowing, violent sneezing, nasal bone, sinus fracture and other damage to the local blood vessels; ② nasal foreign body, commonly found in children, manifested as one side of the nasal cavity bleeding, bloody mucous; ③ inflammation, nasal cavity, sinus inflammation damage to the mucosal blood vessels; ④ tumors, such as nasopharyngeal fibrous hemangioma bleeding is more intense, nasopharyngeal carcinoma, etc. may be manifested in the blood in the snot, and so on. The systemic causes of nosebleed include acute febrile infectious diseases such as influenza, hemorrhagic fever, measles, etc.; cardiovascular diseases such as hypertension, vascular sclerosis, congestive heart failure; hematological diseases such as hemophilia, thrombocytopenic purpura, etc., chronic liver and renal diseases. It is recommended that patients with nosebleeds consult a doctor in time to clarify the cause of the disease and follow the doctor’s instructions for treatment.