What causes stomach pain and acid reflux?
Gastric pain and acid reflux—often described as a burning sensation in the upper abdomen or behind the breastbone—are commonly caused by gastroesophageal reflux disease (GERD) or functional dyspepsia. In GERD, the lower esophageal sphincter (LES) becomes incompetent, allowing gastric acid to flow backward into the esophagus, leading to heartburn, regurgitation, and sometimes epigastric discomfort. Functional dyspepsia, on the other hand, involves chronic or recurrent upper abdominal pain or discomfort without evidence of structural disease (e.g., no ulcer, tumor, or inflammation on endoscopy); it may be linked to gastric hypersensitivity, delayed gastric emptying, or altered gut-brain axis signaling.
Other important causes include Helicobacter pylori infection, which can trigger gastritis or peptic ulcer disease—both associated with epigastric pain and increased acid perception. Nonsteroidal anti-inflammatory drugs (NSAIDs), excessive alcohol intake, smoking, and chronic stress may also impair mucosal defense mechanisms, predisposing individuals to acid-related injury. Less common but clinically significant etiologies include gastric or duodenal ulcers, erosive esophagitis, Zollinger-Ellison syndrome (a gastrin-secreting neuroendocrine tumor causing hypergastrinemia and profound acid hypersecretion), and, rarely, gastric malignancy—particularly in older patients or those with alarm features such as unintentional weight loss, anemia, dysphagia, or persistent vomiting.
A thorough evaluation—including detailed history (timing, triggers, associated symptoms), physical examination, and targeted testing (e.g., H. pylori stool antigen test or urea breath test, upper endoscopy when indicated)—is essential to distinguish benign from serious pathology. Empiric proton pump inhibitor (PPI) therapy may be appropriate for typical GERD symptoms, but persistent or atypical symptoms warrant further investigation to rule out organic disease.