A blood clot in the legs or lung, infection in the incision, or a leak from the stomach into the abdominal cavity or location where the intestine is connected resulting in peritonitis, are risks of gastric bypass surgery, according to WebMD. Gallstones, anemia and osteoporosis are additional side effects.
Individuals who undergo gastric bypass surgery may experience pouch stretching as the stomach gets larger over time and reverts back to its original size, states WebMD. Dangerous stomach acid can leak into other parts of the body and damage organs. The band that is closing off part of the stomach may disintegrate, or the band and staples may fall apart, reversing the procedure. Because the part of the intestine where many minerals and vitamins are absorbed is bypassed, patients may have deficiencies in vitamins, iron, calcium or magnesium, leading to conditions such as osteoporosis.
When food moves too quickly from the stomach to the small intestine, called dumping syndrome, bypass patients can experience weakness, sweating, fainting, diarrhea and nausea after eating, explains WebMD. Gallstones are more likely to develop after weight loss, so medications are used to prevent this. Kidney stones are also common. Hernias may develop due to the surgical incisions or the twisting of the intestine around itself. Eating more than the stomach can hold often results in vomiting.