Study Finds Mounjaro and Zepbound More Effective Weight Loss Treatments Than Ozempic, Wegovy

Diabetes and weight loss medications made with the active ingredient in Mounjaro and Zepbound (tirzepatide) may lead to “significantly greater weight loss” than the ingredient used in Ozempic and Wegovy (semaglutide), according to a new study that compared the effectiveness of the blockbuster treatments.

Each of the medications are part of a new class of drugs, known as glucagon-like peptide-1 receptor agonists (GLP-1 RAs), which work by delaying gastric emptying and promoting a feeling of fullness. Given the overall effectiveness of the drugs at reducing weight, Ozempic, Wegovy, Mounjaro and Zepbound are now used by millions of Americans, and there has been little to differentiate the treatments.

Since each of the medications were associated with similar risks of gastrointestinal side effects, such as stomach paralysis, blockages, pancreatitis and gallbladder problems, researchers suggested in findings published this week in the medical journal JAMA Internal Medicine that Eli Lilly’s tirsepatide-based drugs may be the better alternative than Novo Nordisk’s semaglutide-based drugs.

However, the researchers only looked at the diabetes treatment dosages, not those specifically tailored to promote weight loss.

GLP-1 Side Effect Concerns

Ozempic (semaglutide) was initially introduced for the treatment of people with Type 2 diabetes in late 2017. However, amid aggressive advertisements that promoted the weight loss benefits, Ozempic has been increasingly prescribed as a diet drug in recent years, leading Novo Nordisk to introduce a higher dose version of semaglutide under the brand name Wegovy, which is specifically approved as a diet drug, but contains the same active ingredient.

Eli Lilly has also introduced two competing drugs in the same GLP1-RA class, which contain the pharmaceutical ingredient tirzepatide; including Mounjaro, which was approved for diabetes treatment in 2022, and a weight loss version of the drug approved by the FDA last year under the brand name Zepbound.

Although advertisements promote the drugs as safe and effective, concerns have emerged over the past year about the risk of gastrointestinal side effects from Ozempic, Wegovy, Mounjaro and Zepbound, amid reports of users experiencing painful stomach paralysis or blockages, which can result in a number of severe health complications.

As a result of the drug makers’ failure to adequately warn about this risk, thousands of former users are now pursuing Ozempic lawsuits, Wegovy lawsuits and Mounjaro lawsuits against the manufacturers, and many consumers have been looking for answers about which of the drugs is the best weight loss treatment option.

In this new report, a team of researchers led by Dr. Patricia J. Rodriguez, of Truveta, Inc., conducted a cohort study of 18,386 overweight or obese patients given Ozempic of Mounjaro between May 2022 and September 2023, which at that time were specifically for Type 2 diabetes treatment. The patients’ weight outcomes were recorded and assessed until November 3, 2023. Not all patients given the medications had diabetes, the researchers noted.

According to the findings, patients taking either drug were most likely to achieve at least 5% weight loss withing one year of treatment. However, that weight loss goal was 76% more likely to be achieved by Mounjaro recipients, than those injected with Ozempic.

The researchers also noted that, throughout the study, those given Mounjaro recorded more weight loss at their three-month, six-month, and one-year follow-ups.

However, the researchers noted that there were high rates of discontinuation among users of both drugs, often due to gastrointestinal side effects.

The most frequently reported side effects for both Mounjaro and Ozempic were gastroenteritis, which affected 19.75 out of every 1,000 Mounjaro user person-years, compared to 20.07 per 100,000 to Ozempic. That difference is not considered statistically significant. However, Ozempic was linked to a slightly higher rate of gastroparesis during the study, with 4.81 incidents per 1,000 person-years, compared to Mounjaro’s 3.61.

Ozempic and Mounjaro side effects were also linked to reports of pancreatitis, bowel obstruction, gallbladder inflamation and gall stones

“In this large, propensity-matched, cohort study, individuals with overweight or obesity treated with tirzepatide were significantly more likely to achieve clinically meaningful weight loss and larger reductions in body weight compared with those treated with semaglutide. Consistent treatment effect estimates were observed in subgroups with and without T2D (Type 2 Diabetes),” the researchers concluded. “Future work is needed to compare the effect of tirzepatide and semaglutide on other key end points (eg, reduction in major adverse cardiovascular events).”

Mounjaro and Ozempic Lawsuits

While the findings of this latest study appear to put Mounjaro in a better light, both manufacturers face still-evolving litigation over the same types of gastrointestinal side effects which led some participants to quit, or potentially need additional medical treatment.

Given common questions of fact and law raised in complaints brought throughout the federal court system, the U.S. Judicial Panel on Multidistrict Litigation established coordinated pretrial proceedings for all GLP-1 RA drug lawsuits, centralizing claims brought throughout the federal court system in the Eastern District of Pennsylvania, for coordinated discovery and pretrial proceedings.

As part of the coordinated management of the growing litigation, it is expected that the parties will identify a small group of “bellwether” cases to prepare for early trial dates, which will help help gauge how juries may respond to certain evidence and testimony that will be repeated throughout the claims. However, if the parties are unable to negotiate GLP1 settlements or another resolution for the litigation following any early test trials, each individual lawsuit may later be remanded back to the U.S. District Court where it was originally filed for a separate trial date in the future.