Phlegmonous esophagogastritis is a rare and life-threatening condition characterized by purulent inflammation of the submucosal and muscularis layers of the esophagus and stomach. We report the case of a 59-year-old male with a history of hypertension and prior herbicide ingestion who presented with fever, sore throat, chest pain, and progressive abdominal pain. Initial misdiagnosis of pancreatitis delayed treatment. Endoscopy revealed extensive mucosal detachment, submucosal edema, purulent exudates, and fistula formation, while computed tomography (CT) demonstrated gastric wall thickening and intramural gas. Microbiological analysis identified