Regurgitation

Involuntary backward flow or passive expulsion of previously ingested gastric contents into the esophagus or mouth, without the forceful abdominal contractions characteristic of vomiting. Common causes are acid reflux (GERD), hiatal hernia, achalasia, lifestyle factors (overeating, smoking, alcohol), physical pressure (obesity, pregnancy), medications (NSAIDs, calcium channel blockers), and esophageal obstruction (stricture, Zenker diverticulum).