Ileus

Ileus means the intestines stop moving. Not blocked by an obstruction — just paralyzed, so nothing passes through. The symptoms are severe bloating, abdominal pain, vomiting, and no gas or stool at all. It is a hospital problem, and it can be dangerous if it goes on.

Ileus appears in the postmarketing adverse-reaction sections of the Wegovy, Zepbound, Mounjaro, Saxenda, Ozempic and Foundayo labels, listed alongside intestinal obstruction and severe constipation including fecal impaction. Postmarketing means these reports came in after approval, from a population of unknown size, so the labels cannot attach a frequency to them. That is an honest statement of uncertainty, not a dismissal.

The mechanism is a logical extension of how these drugs work. GLP-1 medications slow gastric emptying by design, and the same signaling slows the rest of the digestive tract. For most people that means constipation. In rare cases the slowdown goes far enough that the bowel stops.

The confusion that matters clinically is distinguishing this from ordinary GLP-1 constipation, which is extremely common and manageable with fiber, fluids and a stool softener. The dividing line is whether anything is passing. Constipation that has become no bowel movements and no gas, with a hard swollen belly and vomiting, is not a fiber problem. A 2023 population study in JAMA examined gastrointestinal adverse events including bowel obstruction in people using GLP-1 agonists for weight loss, which is what brought the issue into mainstream attention.

Ask your prescriber, before you need to know, what their escalation plan is for constipation — at what point they want a call, and at what point they want you in an emergency room. Anyone with a history of abdominal surgery, adhesions or prior obstruction should raise it before the first dose. Our ileus warning review and constipation protocol go further.