Many people with H. pylori infection will experience no symptoms, while others may develop serious complications, including stomach ulcers and inflammation of the stomach lining. Gastric cancer is the most severe consequence of an H. pylori infection. Gastric MALToma, a form of lymphoma, may be treated with H. pylori eradication therapy and has a better prognosis than gastric cancer. H. pylori infection is also associated with esophageal cancer, and may play a role in a condition of low blood platelets (idiopathic thrombocytopenic purpura).
The prognosis for treatment and eradication of H. pylori bacteria is usually excellent, even in patients with complications, such as gastric MALToma. However, the prognosis becomes poor for patients who develop stomach cancer or esophageal cancer. The rate of reinfection is very low (1 to 2 percent). However, children and females have a higher incidence of reinfection (5 to 8 percent).