People prescribed semaglutide – the active ingredient in medications commonly used for weight loss, like Ozempic and Wegovy – have a higher risk of developing rare but serious gastrointestinal conditions, including stomach paralysis. That’s the conclusion of an analysis of the side effects associated with the weight loss medications.
Ozempic and Wegovy belong to a new class of highly effective weight loss drugs which work by mimicking a hormone – GLP-1 – that encourages us to feel satiated after eating. Both drugs contain a so-called GLP-1 agonist, semaglutide, as their active ingredient. Similar drugs contain different GLP-1 agonists, including one named liraglutide. While these drugs have been used to treat type 2 diabetes for over a decade, they were only recently approved by the US Food and Drug Administration for people with obesity. As such, relatively little is known about the long-term side effects of taking GLP-1 agonists for weight loss.
To plug that knowledge gap, Mohit Sodhi at the University of British Columbia in Canada and his colleagues used a large health database that includes 16 million people in the US and captures information on 93 per cent of the country’s out-of-hospital prescriptions and diagnoses between 2006 and 2020.
The researchers found 4757 participants with obesity who were prescribed either semaglutide or liraglutide during this period. None of them had diabetes, which suggests they were given the drug for off-label use – presumably to help them lose weight.
The team then compared the medical history of these participants to the medical histories of a second group of 654 people in the database who had obesity and who were prescribed a different weight loss medication called naltrexone/bupropion.
After adjusting for possible confounding variables including age, sex and alcohol use, the researchers found that people using semaglutide or liraglutide were significantly more likely to develop rare but serious gastrointestinal conditions than those using naltrexone/bupropion. They had more than double the risk of gastroparesis, also known as stomach paralysis, and triple the risk of an intestinal blockage. Additionally, their risk of pancreatitis, or inflammation of the pancreas, was eight times higher than it was for people using naltrexone/bupropion.
These findings suggest that GLP-1 agonists, such as Ozempic and Wegovy, may heighten the risk of serious gastrointestinal conditions. People must be made aware of these risks, rare though they are, especially given the widespread use of these drugs, says Sodhi. “People who are otherwise healthy but want to lose a bit of weight may not be willing to accept [these] possible adverse events,” he says.
“There is definitely a risk of gastrointestinal side effects [with these medications],” says Reshmi Srinath at Mount Sinai Hospital in New York City. “But because the benefits of them are so great in terms of weight loss and reducing complications of obesity, I think we have to take a personalised approach with each patient.”
Some GLP-1 agonists, including Ozempic and Wegovy, are manufactured by Novo Nordisk, a Danish pharmaceutical company. “Patient safety is a top priority. We work closely with the US Food and Drug Administration to continuously monitor the safety profile of our medicines,” a spokesperson for the company told New Scientist. Currently, Novo Nordisk has listed gastroparesis and pancreatitis as potential side effects of Ozempic, Wegovy and other similar products. The spokesperson also noted that many of these products were unavailable until relatively late in the study period explored in the new research, and that Wegovy did not become available until the study period had ended.