The label for Novo Nordisk's weight loss drug Ozempic now acknowledges some users' reports of ileus, or intestinal blockage.
In its update, however, the FDA said it's difficult to confirm a causal relationship between the side effect and the drug.
"Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure," the label says.
Wegovy and Mounjaro, also GLP-1 agonist medications, already acknowledge reports of ileus on their labels. Novo Nordisk is the maker of both Ozempic and Wegovy, which both use an injection of semaglutide.
In a statement to CNN, Novo Nordisk said, "Gastrointestinal events are well-known side effects of the GLP-1 class," adding, "For semaglutide, the majority of GI side effects are mild to moderate in severity and of short duration. GLP-1's are known to cause a delay in gastric emptying, as noted in the label of each of our GLP-1 RA medications. Symptoms of delayed gastric emptying, nausea and vomiting are listed as side effects."