The causes of frequent nosebleeds include allergic rhinitis, deviated nasal septum, nasal hemangioma and high blood pressure. 1. Allergic rhinitis: patients are often exposed to allergenic substances that trigger the body to have an allergic reaction. Part of the patients may unconsciously digging and rubbing the nose due to nasal itching, which may cause erosion and ulceration of the nasal mucosa, and then nosebleed, so that frequent nosebleed can be seen. 2. Deviated nasal septum: the convex surface of the nasal septum in the deviated part is weak because of its mucous membrane, and the flow direction of the air current changes here, which often causes the mucous membrane to be dry, so that the mucous membrane and blood vessels rupture and bleed, and therefore frequent nosebleeds can be seen. 3. Nasal hemangioma: patients may have capillary hemangioma in the defective or thin mucous membrane of the front and lower part of nasal septum due to chronic inflammation, trauma and other reasons. The tumor is soft and easy to bleed due to environmental stimulation or mechanical injury, so it can be seen in the case of frequent nosebleed. 4. Hypertension: hypertensive patients in emotional excitement, coughing, constipation and other situations can often make the blood pressure increase, some of the patients in the nasal cavity capillary rupture, and then bleeding, so that it has a recurrent and difficult to control, so it can be seen in the case of frequent nosebleeds. Frequent nosebleeds may also be caused by blood disorders such as coagulation disorders, and it is recommended to consult a hospital in time to find out the cause of the disease and give targeted treatment according to the cause of the disease.