Bleeding from the mouth is usually checked for oral cavity, blood tests and coagulation. Oral bleeding is usually caused by bad habits or periodontal disease. 1. Oral examination: Bleeding from the mouth may be caused by periodontitis, gingivitis, etc. It usually occurs after brushing teeth or biting hard objects, so you can go to the hospital and have an oral examination under the advice of the doctor to find out the cause of bleeding. 2. Blood test and coagulation: Bleeding from the mouth may also be caused by blood system diseases, it is recommended to take blood tests under the guidance of a doctor to check the blood test and coagulation function to exclude whether there is spontaneous bleeding. Patients with oral bleeding are advised to go to the hospital for examination in a timely manner, and under the guidance of the doctor to carry out reasonable treatment, so as to avoid delaying the condition.