There are many causes of oral bleeding, such as traumatic factors, oral diseases, medication factors, blood diseases and so on. 1. Traumatic factors: patients eating too hard food, dental restorations do not fit, etc., may lead to trauma to the oral mucosa, thus causing oral bleeding. 2. Oral diseases: daily inattention to oral hygiene, not timely brushing, may induce periodontitis, gingivitis, thus causing red and swollen gums, oral bleeding and other phenomena. 3. Drug factors: long-term use of some drugs can also lead to oral bleeding, such as aspirin, the drug will destroy the body’s blood clotting mechanism, so the phenomenon of spontaneous bleeding. 4. Blood diseases: leukemia, thrombocytopenia and other diseases can cause coagulation dysfunction, which can lead to bleeding in the mouth. Causes of oral bleeding, if the phenomenon occurs for a long time, it is recommended that patients go to the hospital in time to improve the examination, a clear diagnosis, identify the causes of standardized treatment.