This will be a prospective randomized control trial with a total of 142 patients. Patients who undergo laparoscopic or open colorectal resection, small bowel resection, or ileostomy reversal with small bowel resection that subsequently develop postoperative ileus will be eligible for enrollment. If they meet inclusion/exclusion criteria, they will be randomized at the time of diagnosis of postoperative ileus to receive Entereg as rescue therapy or to receive conservative standard care.