The clinical course and severity of pancreatitis might vary largely. Pancreatitis‐related thoracic complications might be life‐threatening but frequently ignored. We report an alcoholic patient who initially presented to the emergency department with community‐acquired pneumonia, acute respiratory failure and acute‐on‐chronic pancreatitis with massive pancreatic pleural effusion. Subsequently, he developed insidiously pancreatitis‐related intra‐abdominal, mediastinal pseudocysts, and unexpectedly sudden onset of cardiac tamponade. Although tamponade‐related haemodynamic instability improved soon after timely diagnosis and emergent pericardial drainage, his recovery period was prolonged. His serum amylase and lipase were persistently elevated until definitive treatment with endoscopic retrograde cholangiopancreatography‐assisted removal of pancreatic duct stones. Pancreatitis‐related cardiac tamponade is rare but lethal without prompt diagnosis and management. We reviewed pancreatitis‐related thoracic complications, particularly for cardiac tamponade, and discussed about the pathophysiology and management options.