A specific class of bacteria known as Helicobacter pylori normally resides in the mucosal layer of the stomach and small intestine. Usually, the Helicobacter pylori bacteria cause no harm to the mucosal layer, but in some cases, the excess of this bacterium leads to the inflammation of the gastric inner lining. The inflammation of the gastric inner layer produces ulcers. The pylori bacteria are contagious, and their transmission happens through food and water. The close contact between the people, such as kissing, might become the cause of the spread of this bacterium.
The use of some medications other than NSAIDs like anticoagulants, steroids, alendronate (Fosamax), low dose aspirin, risedronate (Actonel), selective serotonin reuptake inhibitors (SSRIs) increases the chances of the development of open and painful sores in the stomach lining. The ingredients of these medications irritate the stomach lining and decrease the secretion of mucosa in the lining.