Side effects of bariatric surgery can be categorized as short-term and long-term. Short-term includes postoperative bleeding and infection, anastomotic fistula, intestinal obstruction, and sleep apnea syndrome. Long-term includes anemia, malnutrition, gastroesophageal reflux disease and so on. 1. Bleeding and infection: postoperative wound bleeding or inflammatory manifestations such as redness, swelling, heat and pain may occur. 2. Anastomotic fistula: If pus accumulates in the wound, it suggests that anastomotic fistula may exist. 3. Intestinal obstruction: there may be paroxysmal abdominal cramps, loss of appetite, constipation, vomiting, inability to defecate or pass gas, abdominal distension and other symptoms. 4. Sleep apnea syndrome: obese patients may be accompanied by sleep apnea syndrome due to the influence of postoperative anesthesia. 5. Anemia, malnutrition: gastric bypass surgery may cause gastrointestinal absorption disorder, resulting in vitamin deficiency, malnutrition, anemia and other diseases. 6. Gastroesophageal reflux: gastric resection surgery may cause gastroesophageal reflux disease and so on. If you have discomfort after weight loss surgery, you should go to the hospital in time for examination, clarify the cause and then deal with it accordingly.