Stomach ulcer. Endoscope view of a stomach ulcer (white). Ulcers develop when the lining of the stomach is attacked by digestive juices. This can be caused by the presence of the bacterium Helicobacter pylori or the use of non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin. Symptoms of a stomach ulcer include abdominal pain, vomiting blood and bloody stools. Treatment can include antibiotics, antacids and drugs to prevent the secretion of gastric acids.