Sudden nosebleeds are caused by many reasons, examples are as follows: First, the common one is nasal bleeding caused by digging the nose and dealing with nasal mucous membrane erosion caused by nasal hair. Second, the most common cause is high blood pressure caused by hypertension, resulting in nosebleeds. Third, many other causative factors can lead to nasal bleeding, such as deviated nasal septum, dry rhinitis, atrophic rhinitis, nasal foreign body and other causes. Fourth, check whether there are hematological diseases, such as leukemia, idiopathic thrombocytopenia, etc. Fifth, nasal trauma, hemangioma, necrotic nasal polyp, etc. can also trigger nasal bleeding. If the bleeding is too frequent, you still need to go to the ENT department to do the treatment, so as not to delay the treatment and cause acute hemorrhagic shock.