Helicobacter pylori, or H. pylori, is a type of bacteria found in the stomachs of many people. This infection usually develops during childhood, but most people with H. pylori do not have symptoms, and their infection does not cause problems.
However, in some children and adults, H. pylori causes digestive illnesses, including gastritis, which is inflammation of the stomach lining. It can also cause ulcers in the stomach or first part of the small intestine, called the duodenum and on rare occasions it may cause bleeding. These conditions are uncommon in children, but they can cause painful symptoms. If H. pylori is not treated, it can raise the risks of stomach cancer later in life.