Novo Nordisk's weight-loss drugs pose small risk of severe stomach complications: study

People who use Novo Nordisk’s popular weight-loss drugs are taking on a small risk of developing severe stomach problems, according to research conducted by the University of British Columbia and published Thursday in the Journal of the American Medical Association.

The first-of-it-kind investigation indicates a link between Novo’s popular GLP-1 products and the gastrointestinal conditions gastroparesis, pancreatitis and bowel obstruction. In the report, the investigators emphasized that the risk was very small.

Previous studies of GLP-1 drugs have noted an increased risk of these rare stomach disorders for diabetes patients. But this was the first time the risk was demonstrated in people taking the drugs for weight loss, researchers pointed out.

The study examined the health insurance claims of 613 patients on Novo’s semaglutide products and 4,144 patients on Novo’s GLP-1 liraglutide (Saxenda) from a large database of 16 million patients between 2006 and 2020.

Novo's semaglutide is marketed as Ozempic for patients with diabetes and as Wegovy for those with obesity. Both drugs are newer than Saxenda, which launched in 2015.

Those patient groups were compared to 654 patients using bupropion-nalrexone (Contrave), a non-GLP-1 weight-loss treatment which launched in 2014.

All of the patients were prescribed the drugs for weight loss and none had diabetes.

Compared to patients on Contrave, those on the GLP-1 drugs were 9.1 times more likely to have pancreatitis, 4.2 times more likely to have a bowel obstruction and 3.7 times more likely to develop gastroparesis, the study found.

The incidence of pancreatitis, which is an inflammation of the pancreas, was 0.8% for those on liraglutide compared to 0.5% for semaglutide patients. Gastroparesis, which is also called stomach paralysis or delayed gastric emptying, occurred in 1% of semaglutide users, compared to 0.7% of liraglutide patients.

There were no cases of bowel obstruction in patients on semaglutide, compared to a 0.8% rate for liraglutide users. Bowel obstruction is a mechanical blockage in the intestines.

Contrave users experienced gastroparesis at a 0.4% rate and pancreatitis and bowl obstruction at a 0.2% rate for each. 

The research also showed there was no increased incidence of biliary disease for GLP-1 patients.

On the labels of Ozempic, Wegovy and Eli Lilly’s GLP-1 drug Mounjaro, the FDA already warns of another digestive condition—ileus, which is a non-mechanical blockage of the small intestine.

Last month, when the warning was added to the label of Ozempic, a Novo spokesperson pointed out that the company’s GLP-1 drugs have been on the market for more than 15 years for diabetes and eight years for weight loss.

“Semaglutide has been extensively examined in robust clinical development programs, large real world evidence studies and has cumulatively over 9.5 million patient years of exposure,” the Novo spokesperson wrote.

As demand for the drugs has skyrocketed, scrutiny of their side effects has ratcheted up.

In August, a Louisiana woman sued both Novo and Lilly, claiming that use of Ozempic and Mounjaro caused severe stomach problems.

At the time, a Novo spokesperson said gastrointestinal events are a "well-known side effects of the GLP-1 class." Both companies said patient safety is a top priority.

“For semaglutide, the majority of GI side effects are mild to moderate in severity and of short duration," the Novo spokesperson added.