Old nosebleeds may be caused by bad habits, nasal swelling, nasal inflammation, nasal septum deviation, coagulation dysfunction and other reasons. 1. Bad habits: often picking the nose with hands, pulling out nose hairs, may cause local mucous membrane, skin damage caused by old nosebleeds. 2. Nasal swelling: for example, nasal hemangioma, papilloma, etc., which can cause frequent nosebleeds. 3. Deviated nasal septum: the structure of nasal septum is abnormal, and the nasal septum is deviated to one side causing nosebleed. 4. Coagulation dysfunction: for example, thrombocytopenia leads to coagulation dysfunction, which can also cause old nosebleeds. There may be other reasons for nosebleeds, so it is recommended that you consult a doctor in time to find out the cause of the problem and follow the doctor’s instructions.