Gastric and duodenal ulcers usually cannot be differentiated based on history alone, although some findings may be suggestive (see Diagnosis). Epigastric pain is the most common symptom of both gastric and duodenal ulcers. It is characterized by a gnawing or burning sensation and occurs after meals—classically, shortly after meals with gastric ulcer and 2-3 hours afterward with duodenal ulcer.