They may damage this protective lining triggering inflammation, which in turn causes the stomach to secrete more acid. Additionally, the loss of mucous allows normally occurring stomach acid, and other digestive enzymes, to come in direct contact with the stomach wall, causing damage. The duodenal wall becomes susceptible in the same way. H. pylori may also trigger increased production of stomach acid, so the existing mucous barrier cannot continue to protect the stomach or duodenal walls. Helicobacter pylori infection is common, and is probably contacted through food or other oral contaminants.
Many people carry the bacteria in their systems but have no symptoms, and no ulcer is formed.
A number of other causes are responsible for damaging the inner lining of the stomach or duodenum, leading to ulcer formation. These include ingestion of aspirin, ibuprofen, anti-arthritic medications, and alcohol. While the most common symptom of a peptic ulcer is pain, it is possible to have a peptic ulcer even without any symptoms at all. Other symptoms may include nausea, vomiting, loss of appetite and feeling bloated. Pain is often described as burning, gnawing, or stabbing and is located in the central upper abdomen.