Vomiting blood from the mouth for no reason may be related to gastrointestinal diseases, esophageal diseases, blood diseases and other reasons. 1. Gastrointestinal diseases: such as peptic ulcer, due to the ulcer invades the blood vessels under the mucous membrane, which may cause blood vessel rupture and lead to vomiting blood. 2. Esophageal diseases: such as esophageal cancer, which may cause gastrointestinal bleeding in patients with more serious conditions, and they may vomit blood or vomit with blood. 3. Blood diseases: such as hemophilia, due to blood clotting disorders may cause gastrointestinal bleeding and the phenomenon of vomiting blood from the mouth. It is recommended that people who vomit blood from the mouth for no reason should go to the hospital in time to clarify the cause of the disease and carry out standardized treatment under the guidance of the doctor in order to avoid delaying the condition.