Suddenly spitting up a few mouthfuls of blood may be caused by peptic ulcer, cirrhosis of the liver, digestive tract tumors and other reasons. 1. Peptic ulcer: for example, gastric ulcer, duodenal ulcer, ulcer bleeding can lead to vomiting blood, and patients are often accompanied by stomach pain, acid reflux, heartburn and other symptoms. 2. Cirrhosis: elevated portal vein pressure caused by cirrhosis can lead to rupture of the esophagogastric fundus vein and bleeding leading to vomiting of blood. Patients should do liver and gallbladder ultrasound, liver function and other related tests. 3. Tumor of digestive tract: for example, stomach cancer, esophageal cancer and other tumors rupture and bleeding will cause vomiting blood. Patients should do pathological analysis. There are many other causes of sudden vomiting of blood, which should be taken seriously, consult the doctor in time to find out the cause of the disease and follow the doctor’s instruction for further treatment or therapy.