The common bleeding after tooth extraction are as follows: 1. Blood diseases, such as anemia, leukemia, hemophilia, thrombocytopenic purpura, factor VIII deficiency, etc., which are mainly coagulation disorders. 2, patients with cardiovascular diseases, taking anticoagulant drug therapy, such as patients after heart surgery taking aspirin, warfarin, etc., are prone to bleeding due to inhibition of coagulation mechanisms. 3, hepatitis patients, hepatitis patients with impaired liver function, resulting in impaired synthesis of coagulation factors, prone to bleeding during and after tooth extraction surgery. 4. Menstrual period: When teeth are extracted during menstruation, compensatory bleeding may occur, resulting in increased bleeding and prolonged bleeding time. 5. Patients with hypertension: Patients with hypertension have elevated pressure of peripheral small vessels and capillaries, resulting in more bleeding during tooth extraction. 6. Patients with local chronic inflammation. Local chronic inflammation can lead to capillary hyperplasia and congestion in local tissues, resulting in increased bleeding. 7. Central hemangioma of the jaw bone, this disease is more dangerous and there may be heavy bleeding or more than one bleeding after tooth extraction.