Amoxicillin is useful in duodenal ulcers caused by Helicobacter pylori. The etiology and pathogenesis of duodenal ulcers are multifactorial, such as the invasive effect of gastric acid on the gastric mucosa, the infection of H. pylori, the effect of drugs, and abnormalities in mucosal defense and repair. The treatment of duodenal ulcers caused by various etiologies is different, and amoxicillin is mainly used to treat duodenal ulcers caused by H. pylori infection. Amoxicillin is a β-lactam antibiotic, mainly by interfering with the biosynthesis of the mucous fibers of the bacterial cell wall, thus causing the bacteria to rapidly dissolve and rupture and die, and playing an antibacterial effect. However, it can not play a normal antibacterial effect in an acidic environment, generally the clinical use of amoxicillin and another antibiotic (such as furazolidone, etc.), proton pump inhibitors (such as omeprazole, etc.), and bismuth (such as bismuth potassium citrate) quadruple combination of drugs to eradicate H. pylori, in order to achieve the purpose of the root of the treatment of duodenal ulcers. If you need to use medication, it is recommended to use medication under the guidance of a doctor, not blindly self-medication to avoid adverse effects.