The main symptoms of duodenal ulcer include upper abdominal bloating, belching, acid reflux, nausea, vomiting, heartburn, poor appetite, and indigestion. A duodenal ulcer can be diagnosed through a gastroscopy, which reveals the presence of an ulcer in the duodenum. The primary cause of duodenal ulcers is infection by Helicobacter pylori, hence a Carbon-14 breath test is recommended to confirm the presence of H. pylori infection. Roughly 90%-100% of patients with duodenal ulcers are infected with H. pylori. Another common cause is the digestion of the stomach itself by stomach acid and pepsin. Treatment primarily involves eradicating H. pylori, suppressing acid, protecting the stomach, enhancing gastric motility, and protecting the gastric mucosa, with the treatment duration being about six weeks.