What’s the difference between Wegovy and Mounjaro?

While they’ve been around for over a decade, the growth of GLP-1s has mushroomed recently. And though they may look identical at first glance — liraglutide, semaglutide, tirzepatide — each ‘tide has its own truth and benefit. Take Wegovy vs. Mounjaro, for example. Are both GLP-1s? Yes. Are there some pretty major differences between them? Absolutely.

While your provider or virtual weight-loss clinic will ultimately guide you to the best GLP-1 for you, knowledge is power. So, with that, here’s what you need to know about Wegovy vs. Mounjaro.

Wegovy is a brand name of the GLP-1 semaglutide that’s FDA-approved for weight loss. This is also the same active ingredient prescribed in Ozempic, which is FDA-approved for type 2 diabetes. 

Semaglutide mimics GLP-1, a hormone naturally produced by your body that helps manage your appetite, induces feelings of fullness, decreases blood sugar fluctuation, and slows the rate of gastric emptying. “GLP-1 has powerful appetite suppressant effects in the brain — enough to cause significant weight loss,” says Dr. Charlie Seltzer, M.D., an obesity specialist based in Philadelphia.

Mounjaro is also a GLP-1, a brand name for the drug tirzepatide that’s FDA-approved to improve glucose in people with type 2 diabetes. Zepbound is the brand name for the drug tirzepatide that’s FDA-approved for weight loss. 

Unlike Wegovy, Mounjaro’s GLP-1 is paired with a GIP, short for glucose-dependent insulinotropic polypeptide, which is another naturally occurring hormone that is produced in the gut. That combo gives Mounjaro a bit of a boost. “It helps to increase insulin to manage blood sugar and amplifies appetite suppressing effects when used in combination with GLP-1,” says Dr. Robert Kushner, M.D., professor of medicine and medical education at Northwestern University Feinberg School of Medicine in Chicago.

Right now, there are no generic versions of either Wegovy or Mounjaro. This can contribute to their relatively high price tag (generics often are sold at much lower prices than brand name versions of drugs).

The biggest differences between Wegovy and Mounjaro — beyond their FDA-approved uses and active ingredients — is that Mounjaro has GIP in addition to GLP-1.

“We know that the GIP makes the GLP-1 work better,” says Seltzer, for instance, by suppressing your appetite more than GLP-1 alone. In addition to that, GIP has its own functions in the body: “The GIP targets white adipose tissue, which is an inflammatory type of fat,” says Dr. Holly Lofton, M.D., professor of medicine and surgery at NYU Grossman School of Medicine and the director of the medical Weight Management Program at NYU Langone Health in New York City. This can improve the function of white adipose tissue, which ultimately helps with triglyceride levels and blood sugar.

Wegovy treats obesity, whereas Mounjaro is approved for those with type 2 diabetes as a way to control blood sugar. Wegovy also has FDA approval for the management of MASH, and for adults who’ve had a previous cardiac event, since it may prevent a second heart attack or stroke, says Lofton. While Mounjaro doesn’t have an additional approval beyond diabetes mellitus type 2, it has shown promise for improving cardiovascular disease.

Wegovy and Mounjaro behave pretty similarly in terms of how you take the medicine and how much medicine is in each dose. “Both semaglutide and tirzepatide are prescribed as weekly, self-administered injections and are started at the lowest dose,” says Kushner. This is 0.25mg for both medications.

After that, the dosages of both medications are gradually increased. “Depending on the occurrence of side effects and change in body weight, they are slowly escalated every month to reach the best therapeutic dose,” Kushner says. (For Mounjaro, the increase in dose primarily depends on your blood sugar levels.)

That final dosage you settle at can vary according to the exact medication you’re on. The maximum dose is 2.4mg for Wegovy and 15mg for Mounjaro. In Seltzer’s experience, most people benefit from being near the maximum dosing for Mounjaro, “whereas more people do okay with more moderate doses of semaglutide,” he says.

In terms of weight loss for patients without diabetes, the two active ingredients have been compared, and tirzepatide (the one in Mounjaro) lead to more weight loss than semaglutide (the ingredient in Wegovy). In studies over 72 weeks, semaglutide led to an average weight loss of 13.7% of participants’ starting weight, while tirzepatide led to an average loss of 20%, as well as great loss in waist circumference.

At the moment, commercial insurance companies may not cover GLP-1 medications to manage obesity, although it largely depends on your exact insurer and plan. Even if your insurance plan does cover these types of drugs, that doesn't mean you automatically qualify, since patients have to meet certain criteria, like a minimum BMI of 30 (or a BMI of 27 with a weight-related health issue like hypertension), to qualify for that coverage.

Mounjaro is a different story. It’s approved for treating type 2 diabetes, which is often considered a qualifying condition that can be covered by insurance — although again, it ultimately depends on your specific plan.

Without insurance, the retail prices are usually well over $1,000 a month for both medications, due in part to a lack of generic versions and the high cost of research and development. But some companies, like Eli Lilly and Company, which manufactures Mounjaro, have savings programs that can help bring down the out-of-pocket cost, so it can help to do research and explore all your options.

The side effects are largely the same for both Wegovy and Mounjaro, the most common being gastric-related issues like nausea and constipation. “The side effects are typically described as mild and predominately occur when the medication dosage is being escalated over the first four months of treatment,” says Kushner.

The most common side effects for both medications tend to be mostly mild; they can include nausea, constipation, vomiting, diarrhea and abdominal pain, primarily due to the slowdown in your digestive tract.

Between Wegovy and Mounjaro, Mounjaro seems to come with less intense side effects. That’s due in part to the addition of GIP. “Dual agonism from GIP provides more of a delay in gastric emptying and has a slight antiemetic effect,”—antiemetic effect meaning that it minimizes nausea and vomiting—”so it causes less nausea even though the stomach is emptying more slowly,” says Lofton.

The serious side effects of Wegovy and Mounjaro are rare. In one semaglutide study (the active ingredient in Wegovy), serious adverse events were reported in nearly 10% of participants, with 7% discontinuing treatment due to adverse events, mainly G.I.-related. For tirzepatide (the ingredient in Mounjaro), the proportion of serious adverse effects depended on the dose and ranged from 6-8%, with the 15-mg dose having the highest proportion of patients who stopped the medication due to serious side effects.

Possible serious side effects include: inflammation of the pancreas, or pancreatitis; gallbladder issues, such as gallstones; low blood sugar; acute kidney injury; hypersensitivity reactions; increased heart rate; suicidal behavior or thinking; and diabetic retinopathy, which is damage to the eye's retina and a complication of diabetes. Your provider can monitor you for these conditions if there's any concern. Mounjaro’s serious side effects can also include serious allergic reactions and severe stomach problems.

Both Wegovy and Mounjaro feature black-box warnings — the most serious kind from the FDA — for the risk of thyroid cancer, since GLP-1s are associated with thyroid C-cell tumors in rats, depending on the dose and duration of treatment. This hasn’t been proven or found in humans, however.

Both medications also have warnings on the label for acute pancreatitis, hypoglycemia (low blood sugar) and acute kidney injury, based on (extremely rare) incidents from clinical trials.

Wegovy and Mounjaro are both GLP-1 agonists, but they have some key differences. Wegovy is just a GLP-1 and is approved for weight loss while Mounjaro is a combination GLP-1 and GIP and is approved for type 2 diabetes. They can both lead to weight loss, with Mounjaro’s potential weight loss more than Wegovy’s. They also both have similar side effects, which tend to be gastrointestinal in nature, and are given the same way via a self-administered weekly injection. Talk to your provider or reach out to one with WeightWatchers Clinic if you have questions about which GLP-1 may be right for you and your needs.