Stomach ulcers can cause hemorrhages from the erosion of a major blood vessel and tear the wall of the stomach or the intestine in the case of a duodenal ulcer, which results in peritonitis. Stomach ulcers can also become malignant.So the answer is yes you can die of a stomach ulcer. A high percentage of both ulcers is caused by the bacterium Helicobacter Pylori other cause are injury to the mucosal lining, excess secretion of hydrochloric acid, genetic predisposition, stress, use of anti-inflammatory medication asprin etc. and smoking.