Pericarditis is an inflammation of the pericardium, often with fluid accumulation. It can be caused by infection (often viral), myocardial infarction, drugs, malignancies, metabolic disorders, autoimmune disorders, or trauma. Acute, subacute, and chronic forms exist. Acute pericarditis is usually idiopathic and manifests as fever, pleuritic chest pain, and an audible pericardial rub by auscultation. Diffuse upwardly concave ST-segment elevations in the initial ECG and pericardial effusion on echocardiography confirm the diagnosis. Acute pericarditis is usually self-limiting (2–6 weeks); therefore, management is conservative. If cardiac tamponade or constrictive pericarditis develops, cardiac output can be severely reduced. Treatment depends on the cause, but general measures include analgesics, anti-inflammatory drugs, colchicine, and rarely surgery.