Suddenly spit out red blood in the morning may be oral bleeding, respiratory bleeding, upper gastrointestinal bleeding and so on. 1. Oral bleeding: gingivitis, periodontitis, oral ulcers, swollen gum tissue, capillaries become brittle and easy to bleed, oral mucosa ulcers can lead to easy bleeding, after a night, can be manifested in the morning spit out red blood. 2. Respiratory bleeding: respiratory bleeding is generally manifested as coughing out of the cough, can be manifested as the morning suddenly spit out red blood, common diseases are bronchodilatation, tuberculosis, lung cancer, pneumonia, etc., often accompanied by coughing, coughing up sputum, shortness of breath, chest tightness symptoms. 3. Upper gastrointestinal bleeding: bleeding from the upper gastrointestinal tract can be vomited from the mouth, which can be manifested as suddenly vomiting red blood in the morning, common diseases include peptic ulcer bleeding, gastric cancer bleeding, gastric mucous membrane bleeding from acute lesions, cirrhosis, esophagogastric fundal varices rupture bleeding and so on, and the vomited blood can be mixed with food residue, gastric juice and other substances, often accompanied by abdominal pain, nausea, vomiting, abdominal distension symptoms. Suddenly vomiting red blood in the morning should go to the hospital, under the guidance of the doctor to check and clarify the cause of treatment.