Gastrointestinal Problems Are Most Common GLP-1 Side Effects, Study Finds

Researchers indicate that signals for other potential side effects of GLP-1 medications, like bone fractures and gallbladder disease, were less certain and require more studies.

Chinese researchers say they conducted the largest and most comprehensive review to date on the side effects of GLP-1 receptor agonists, finding strong evidence linking the drugs to gastrointestinal issues, while other potential safety concerns remained less clear.

The findings were published in JAMA Network Open on March 31, indicating that gastrointestinal problems, including stomach paralysis and bowel obstruction, are the most common complaints by those taking diabetes and weight loss drugs like Ozempic, Mounjaro and Wegovy.

GLP-1 Medications

First created to treat Type 2 diabetes, GLP-1 medications, including Ozempic, Mounjaro, Wegovy, Zepbound, Trulicity, Rybelsus and others, have grown significantly in popularity after they became linked with significant weight loss and beneficial metabolic effects.

However, the findings of a study published in October 2023, linked GLP-1 medications to triple the risk of gastroparesis, or stomach paralysis, compared to non-injectable weight loss medications. In the aftermath, thousands of Ozempic lawsuits, Wegovy lawsuits, Mounjaro lawsuits and other GLP-1 stomach paralysis complaints have been filed by users nationwide.

In addition, a growing number of other lawsuits have been brought in recent months after some of the medications, specifically Ozempic and Wegovy, were linked to GLP-1 vision loss side effects. Plaintiffs say these side effects, being discovered years after the products were placed on the market, are signs the manufacturers either failed to properly test the drugs, or failed to provide adequate warnings about the potential health risks.

GLP-1 Side Effects Study

The new study, led by Dr. Kaijie Yang of First Hospital of China Medical University, involved a review of 60 different meta-analyses of 1,751 randomized clinical trials involving about three million participants. The researchers combed data for incidence of gastrointestinal adverse events, cancer, fractures, respiratory problems, psychiatric side effects, liver problems and other potential complications.

The findings showed the most consistent risks involved gastrointestinal issues, with roughly double the likelihood of nausea, vomiting and diarrhea. While researchers identified some signals suggesting a possible link to pancreatitis, evidence for other side effects, such as gallbladder or biliary disease, was less clear.

The analysis also suggested that GLP-1 medications may offer some protective effects against infections, respiratory diseases, bone fractures and dementia, while findings related to cancer remained inconclusive.

“GLP-1 RAs continue to be a cornerstone of antidiabetic therapy but should not be misconstrued as a panacea. The complex profile that emerged from our findings was characterized by potential neuroprotective and respiratory benefits coexisting with safety signals related to gastrointestinal events, such as nausea and vomiting.”

– Dr. Kaijie Yang, GLP-1 Receptor Agonists and Noncardiometabolic Outcomes

The researchers concluded that the findings make it clear that doctors should approach GLP-1 use as part of individualized therapeutic strategies instead of just being prescribed routinely.

GLP-1 Stomach Paralysis Lawsuits

Drug makers Novo Nordisk and Eli Lilly currently face more than 3,300 GLP-1 stomach paralysis lawsuits filed in federal courts nationwide, with plaintiffs claiming to have suffered severe injuries due to the delayed gastric emptying effects of the medications.

These claims are consolidated into a multidistrict litigation in the Eastern District of Pennsylvania, where U.S. District Judge Karen Marston is overseeing coordinated discovery and pretrial proceedings.

Judge Marston is working with the parties to select a small group of representative cases for bellwether trials, which will allow the parties to gauge how juries may respond to evidence and testimony likely to recur across thousands of similar claims.

GLP-1 Vision Loss Lawsuits

Similarly, Judge Marston is also overseeing a consolidated MDL of GLP-1 vision loss lawsuits, which consists of dozens of claims. These lawsuits began to be filed after a series of studies linked semaglutide-based drugs, like Ozempic, Wegovy and Rybelsus, to a condition known as non-arteritic anterior ischemic optic neuropathy (NAION).

The condition can cause rapid onset of blurred or reduced vision, including blindness. Resulting in optic nerve damage, NAION occurs suddenly and the vision loss is often permanent. More than 50 GLP-1 vision loss lawsuits have already been filed by patients facing such injuries.

The judge is expected to also guide these cases through coordinated discovery, pretrial proceedings and a group of bellwether trials as well.

While the outcomes of these trials will not be binding on other claims for either condition, they will be closely watched to see what kinds of payouts juries award to plaintiffs, which are likely to have a significant impact on negotiations. However, if no settlement is reached following the bellwether trials, Judge Marston is likely to remand the cases back to their originating districts for individual trial dates.

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