Ozempic and Mounjaro Patients Report Potentially Fatal New Side Effect
Officials are studying the link between acute pancreatitis and GLP-1 weight loss drugs.

The effectiveness of modern drugs like Ozempic and Mounjaro has helped revolutionize weight loss and the health issues that come along with obesity. But as with any drug, the number of side effects from these injectable medications is also increasing. Understandably, some affect people’s appearance, while others are even more alarming and can reportedly cause issues such as impaired vision. But now, patients have begun to report a potentially new fatal side effect when taking GLP-1 drugs.
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There may be a link between GLP-1 medications and pancreatic issues.
Health regulators in the U.K. have launched a study into GLP-1 weight loss drugs after hundreds of patients reported pancreatic issues, The Guardian reports. In some instances, there are reports that patients were hospitalized and died as a result.
“Alongside increased usage, we are seeing an upturn in the number of Yellow Card reports mentioning GLP-1 medicines and acute pancreatitis,” a spokesperson for the U.K.’s Medicines and Healthcare products Regulatory Agency (MHRA) said in a statement.
Patients taking one specific weight-loss drug are reporting more complications.
While they have not been conclusively linked to the medications, there have so far been roughly 400 cases of acute and chronic pancreatitis seen in patients taking GLP-1 drugs, The Guardian reports. Over 25 percent of these reported incidents took place this year, with 22 cases seen in patients taking semaglutide-based medications such as Wegovy and Ozempic reported to the MHRA. However, 101 cases of serious pancreatic issues were reported in patients taking tirzepatide medications such as Mounjaro during the same period.
As of May 13, at least 10 of these cases resulted in the death of the patient, the BBC reports. However, it’s unclear whether comorbidities factored into the outcome.
According to Mayo Clinic, pancreatitis is the inflammation of the pancreas, which is a gland located on the back of the stomach that helps in digestion and metabolic function. It typically presents with symptoms such as pain in the upper abdomen (including pain that radiates to the back), tenderness in the belly, fever, elevated pulse, upset stomach, and vomiting.
Some patients who develop acute pancreatitis can see the condition improve on its own. However, it can often require hospitalization and result in serious complications such as breathing problems, kidney failure, and serious infection, per Mayo Clinic.
RELATED: Gynecologist Cautions Women About This “Overlooked” Ozempic Side Effect.
There could be a patient-specific link to the side effect.
To better understand the potential risks, the MHRC is now asking patients who are 18 or older and experienced the side effect and were hospitalized to report it through its Yellow Card program. The agency will contact these patients to see if they’d like to participate in the study, which will likely require a saliva sample kit sent to their homes that will be used to assess each person’s genetic makeup.
“GLP-1 medicines like Ozempic and Wegovy have been making headlines, but like all medicines, there can be a risk of serious side effects,” Matt Brown, PhD, chief scientific officer at Genomics England, said in a statement from the MHRC. “We believe there is real potential to minimise these, with many adverse reactions having a genetic cause.”
Once the study has been completed, Brown added that the agency would “generate data and evidence for safer and more effective treatment through more personalised approaches to prescription, supporting a shift towards an increasingly prevention-focused healthcare system.”
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The drugs’ parent companies responded to the claims.
Pancreatitis is already listed on the Ozempic warning label as a potential side effect in GLP-1 medications. It’s cited as an “uncommon” issue in up to 1 in 100 patients, and urges anyone experiencing symptoms to contact their doctor immediately. Still, Mounjaro manufacturer Lilly issued a statement saying patient safety was its “top priority” in light of the news.
“We take reports regarding patient safety seriously and actively monitor, evaluate and report safety information for all our medicines. Adverse events should be reported under the MHRA’s Yellow Card scheme, but may be caused by other factors, including pre-existing conditions,” the company said, per The Guardian. Lilly added that its warning label also cites pancreatitis as an “uncommon” side effect.
Ozempic and Wegovy parent company Novo Nordisk released a statement from its U.K. branch also stressing that patient safety is of the “utmost importance.”
“Like all medications, side effects can occur and vary from patient to patient. The known risks and benefits of GLP1 medicines are described in the summary of product characteristics,” the company said in its statement, adding that patients should only take the GLP-1 drugs under the supervision of their healthcare providers, who can monitor for potentially dangerous side effects.
“We continuously collect safety data on our marketed GLP-1 medicines and work closely with the authorities to ensure patient safety,” Novo Nordisk U.K. added. “The benefit-risk profile of our GLP-1 medicines remains positive, and we welcome any new research that will improve our understanding of treatments for people living with chronic diseases.”