The use of μ-opioid receptor antagonists significantly reduces bowel recovery time following major abdominal surgery. The use of serotonin receptor agonists may also be of use; however, there is a lack of high-quality homogenous trials to support this. There is good evidence to suggest that ghrelin receptor agonists are not useful for the prevention of postoperative ileus. This evidence concerns the gene GHSR and ileus.