Acute pancreatitis is among the most common gastrointestinal disorders requiring hospitalization. The main causes are gallstones and alcohol use. Patients typically present with upper abdominal pain radiating to the back, worse with eating, plus nausea and vomiting. Diagnosis requires meeting two of three criteria: upper abdominal pain, an elevated serum lipase or amylase level greater than 3 times the normal limit, and imaging findings consistent with pancreatitis. After pancreatitis is diagnosed, the Atlanta classification and identification of the systemic inflammatory response syndrome can identify patients at high risk of complications. Management includes fluid resuscitation and hydration maintenance, pain control that may require opioids, and early feeding. Feeding recommendations have changed and "nothing by mouth" is no longer recommended. Rather, oral feeding should be initiated, as tolerated, within the first 24 hours. If it is not tolerated, enteral feeding via nasogastric or nasojejunal tubes should be initiated. Antibiotics are indicated only with radiologically confirmed infection or systemic infection symptoms. Surgical or endoscopic interventions are needed for biliary pancreatitis or obstructive pancreatitis with cholangitis. One in five patients will have recurrent episodes of pancreatitis; alcohol and smoking are major risk factors. Some develop chronic pancreatitis, associated with chronic pain plus pancreatic dysfunction, including endocrine failure (insulin insufficiency) and/or exocrine failure that requires long-term vitamin supplementation.