There are several common causes of blood in vomit: first, oral diseases should be excluded, such as inflammation of the gums, ulcers, etc.; second, pharyngeal diseases, often caused by chronic cough, causing mucosal damage, resulting in symptoms of blood in vomit; third, lung diseases, such as tuberculosis, lung cancer, bronchial dilatation and other diseases, will have symptoms of blood in vomit; fourth, diseases of the stomach, gastric mucosal damage When bleeding is caused, the symptoms of vomiting with blood will also occur, and in serious cases, blood will be vomited directly. Of course, the above is only from the symptoms to identify, to confirm the diagnosis, it is best to do further clinical examination.