C14 H. pylori is the abbreviation of H. pylori C14 breath test, positive indicates the presence of H. pylori infection in the body, patients will also be accompanied by bad breath, nausea and other discomforts. H. pylori is a bacterium that lives in the gastric mucosa, and its long-term presence can cause inflammation and atrophy of the gastrointestinal mucosa, and even cancer, mainly through the oral-oral or fecal-oral route of infection, and is mostly eradicated clinically through a quadruple protocol. Commonly caused diseases such as chronic gastritis, peptic ulcer, can be judged according to the clinical accompanying symptoms: 1, chronic gastritis: H. pylori can be attached to the mucus layer of the gastric sinus, can not be eliminated by gastric acid, the production of ammonia and vacuolar toxin can lead to chronic damage to the gastric mucosal cells, which leads to chronic gastritis, the examination can be seen in a positive H. pylori C14 breath test. Clinical manifestations can be discomfort, dull pain, burning pain in the upper abdomen, a feeling of fullness after meals, and also symptoms of indigestion such as poor appetite, belching, acid reflux, nausea, and vomiting; 2. Peptic ulcer: including gastric ulcer and duodenal ulcer. Helicobacter pylori infection is an important causative factor of peptic ulcer. On the basis of chronic gastritis, the mucosal cells can be further damaged, and gastric acid erosion leads to lesions reaching the mucosal muscle layer or deeper and ulcers appearing, which can be seen by examination with a positive H. pylori C14 breath test. Peptic ulcers have similar symptoms to gastritis, but also have hunger-like discomfort in the upper abdomen, with long-term persistent episodes or seasonal episodes. Some patients have symptoms related to eating, and postprandial abdominal pain is seen in gastric ulcers, while preprandial or nocturnal abdominal pain is seen in duodenal ulcers and is relieved by eating.