Starting a weight loss treatment may feel daunting, especially since multiple branded and generic treatments are now easily accessible. Likewise, if you’ve been using Mounjaro, you may now be looking for a more cost-effective alternative treatment like Wegovy.

It’s important to know the difference between treatments before deciding which one is right for you. Mounjaro and Wegovy are two of the most popular weight loss medications currently on the market — let’s explore the difference between the two to help you understand which is right for your weight loss goals.

Mounjaro and Wegovy: What are they?

Let’s take a quick look at what these medications are and how they work.

Both Wegovy and Mounjaro are injectable weight loss treatments. Wegovy works by mimicking the naturally occurring GLP-1 hormone in your body. This is a hormone that’s released after you eat, triggering insulin production to help stabilise your blood sugar levels. For this reason, GLP-1 medications were originally developed to treat people with type 2 diabetes. GLP-1s also reduce your appetite and slow gastric emptying, or the rate food leaves your stomach, which helps increase feelings of fullness and reduce your food intake. [1] [2]

Mounjaro works in the same way, but unlike Wegovy, it mimics an additional hormone called GIP (glucose-dependent insulinotropic polypeptide, to be precise). Like GLP-1 medication, GIP also enhances insulin secretion after you eat and reduces appetite. This means that Mounjaro mimics two incretin hormones instead of just one, which can make it more effective.

What is Mounjaro?

Mounjaro is a weight loss medication developed by the pharmaceutical company Eli Lilly. It contains the active ingredient tirzepatide, and it’s unique because it’s a dual agonist medication, targeting both GLP-1 and GIP receptors in the body. In simple terms, Mounjaro provides all the insulin release, appetite regulation and blood sugar control benefits of a GLP-1 medication, but its additional targeting of GIP receptors enhances these effects.

What is Wegovy?

Wegovy is a brand-name medication that contains the active ingredient semaglutide, a GLP-1 agonist. Unlike other GLP-1 treatments such as Ozempic, which was initially designed to treat type 2 diabetes, Wegovy was created as a dedicated weight loss drug. Semaglutide is the same active ingredient in Ozempic, but it’s available in a higher dose in Wegovy for greater weight loss effectiveness.

Similarities between Mounjaro and Wegovy

Both Mounjaro and Wegovy are clinically proven weight loss treatments that target the GLP-1 receptors in your gut and brain to reduce your appetite and help you feel full for longer. They’re both injectable medications that arrive in pre-filled pens, and you administer your doses as ‘subcutaneous injections’ — that means they’re injected into the fatty layer of tissue just under your skin.

The eligibility criteria for Mounjaro and Wegovy is also the same. [3] For a healthcare provider to prescribe either to you, you must have a BMI of 30 or over. You may also qualify for treatment if your BMI is over 27 and you have a weight-related health condition, such as high blood pressure, type 2 diabetes, pre-diabetes, heart disease or raised cholesterol.

Key differences between Mounjaro and Wegovy

There are also some major differences between these two medications, which may impact which treatment plan you’d prefer.

How they work

Mounjaro and Wegovy contain different active ingredients which work in similar ways, but aren’t exactly the same. Mounjaro has the extra benefit of dual GLP-1 and GIP action, while Wegovy works as a GLP-1 agonist.

Average weight loss

Mounjaro and Wegovy are both proven to be effective at aiding weight loss in clinical trials. Research shows that Wegovy has the potential to help you lose 14.9% of your body weight over 68 weeks. [4] Mounjaro, on the other hand, has a higher average weight loss, with a clinical study finding it could reduce your body weight by up to 20.9% over 72 weeks on the maximum dose. [5]

It’s also important to note that the best weight loss results from either medication are gained by combining your treatment plan with sustainable, long-term lifestyle changes, including a reduced-calorie diet and increased physical activity.

Common side effects

Everyone responds to new medications differently, so you may experience different mild side effects from Mounjaro and Wegovy. Generally, the most common side effects patients report are:

• Nausea
• Vomiting
• Constipation
• Diarrhoea
• Headaches
• Fatigue
• Stomach pain
• Injection site reactions (redness or itching)

Serious side effects

Rarely, these injections can cause more serious adverse side effects, including pancreatitis (inflamed pancreas), acute kidney injury (reduced blood flow to kidneys caused by dehydration) and anaphylaxis (allergic reaction). If you have any signs of these side effects, call 999 and seek urgent medical attention.

Mounjaro vs Wegovy: Which is better?

• Both Mounjaro and Wegovy mimic GLP-1, but Mounjaro also mimics GIP, which enhances its effects.
• Both medications help regulate blood sugar levels and appetite to aid weight loss. Mounjaro can help you lose 20.9% of your body weight; Wegovy can help you lose 14.9% in just over a year. 
• Both are weekly injections containing prescription drugs that must be prescribed by a licensed healthcare professional.
• Both may cause side effects.

Interested in medicated weight loss?

We can help you find the most suitable treatment plan for you, and provide support on lifestyle changes, managing side effects and more. Our clinicians assess your medical history and goals so you can get the best results and guidance for your weight loss journey.

Find out what treatment is suitable for you on MedExpress.

References:

1. Collins L, Costello RA. Glucagon-like Peptide-1 Receptor Agonists [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551568/
2. Latif W, Lambrinos KJ, Rodriguez R. Compare And Contrast the Glucagon-like Peptide-1 Receptor Agonists (GLP1RAs) [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572151
3. Four-dose Mounjaro “KwikPen” approved by MHRA for diabetes and weight management [Internet]. GOV.UK. Available from: https://www.gov.uk/government/news/four-dose-mounjaro-kwikpen-approved-by-mhra-for-diabetes-and-weight-management
4. Wilding JPH, Batterham RL, Calanna S. Once-Weekly Semaglutide in Adults with Overweight or Obesity. The New England Journal of Medicine. 2021 Feb 10;384(11):989–1002.
5. Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine [Internet]. 2022 Jun 4;387(3). Available from: https://www.nejm.org/doi/full/10.1056/NEJMoa2206038