Bariatric surgery is a standard treatment for obesity and a number of its complications. Although surgical complications are relatively rare, some patients must return to the emergency department or to a facility far removed in place and time from the original surgery. The purpose of this update is to outline the main reasons for short, medium, and long-term emergency department visits and re-hospitalizations in patients who have undergone bariatric surgery. In the short term, patients may experience non-specific (pulmonary embolism, rhabdomyolysis) and specific (hemorrhage, fistula) complications. Their management is based on a multidisciplinary medical, nutritional, and interventional strategy, with an increasingly important role for surgical endoscopy. In the medium and long term, the reasons for emergency consultation and re-hospitalization are relatively non-specific (abdominal pain, vomiting, excessive or inadequate weight loss). In all cases, complete clinical, laboratory and nutritional assessments are essential. Some long-term postoperative complications are non-specific and require appropriate management: symptomatic gallstones, trocar orifice hernia. Other complications are more specific to each type of bariatric surgery. For gastric banding, these are mainly intragastric band migration and tilting; for sleeve gastrectomy, these are severe reflux, stricture, and delayed fistula; finally, for gastric bypass, these are intestinal obstructions, particularly due to mesenteric breaches, strictures, and anastomotic ulcers. The management of these complications also relies on a multidisciplinary strategy. In conclusion, re-hospitalizations after bariatric surgery are not infrequent and may occur for relatively non-specific reasons. Appropriate clinical, laboratory, and morphological assessments allow for an accurate diagnosis and appropriate management.