Is Wegovy as Effective as Mounjaro?

Wegovy is a weight loss medication from Novo Nordisk. Since becoming available in the UK in 2023, tens of thousands of patients have used Wegovy for weight loss.

But when Eli Lilly released Mounjaro in 2024, it took over from Wegovy as the UK’s leading weight loss medication. In many cases, patients mentioned that Mounjaro’s effectiveness prompted them to choose it.

So which is more effective for weight loss? Wegovy or Mounjaro? Here, we look at both medications and weigh up the evidence.

How Do Mounjaro and Wegovy Work?

Both Mounjaro and Wegovy work in a similar way. However, the treatments have different active ingredients. While Mounjaro’s active ingredient is tirzepatide, Wegovy’s is semaglutide (the same as Ozempic).

Wegovy (semaglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist. When you take it, it interacts with your body’s GLP-1 receptors, which help control your appetite. This interaction reduces hunger, makes you feel fuller for longer, slows digestion and helps to control your cravings.

Mounjaro (tirzepatide) acts on the GLP-1 receptors, but also acts on glucose-dependent insulinotropic polypeptide (GIP) receptors. GIP receptors work in a similar way. By acting on two receptors, Mounjaro offers two pathways to suppress appetite.

Both medications should be combined with a healthier diet and exercise for the best weight loss results. Both are weekly injections, which you inject either in the upper arm, thigh or stomach.

Is Wegovy as Effective as Mounjaro for Weight Loss?

Both Wegovy and Mounjaro have been shown to have excellent weight loss effects.

Studies have shown that, on average, patients using Wegovy’s highest dose (2.4 mg) lost around 17% of their starting weight over 68 weeks. Those using Mounjaro’s highest dose (15 mg) were recorded as losing around 22.5% over 72 weeks.

At first glance, this may suggest Mounjaro is a more effective weight loss treatment than Wegovy. However, these are average figures, meaning some patients lose more, while others lose less.

It’s also worth noting that Mounjaro has six dose strengths, while Wegovy has five.

Patients will typically use each strength for one month before moving up to the next. So patients titrating up on Mounjaro may take longer to reach the highest dose. The gradual increase helps manage tolerability and side effects. But the total time to reach the maximum dose can vary.

Wegovy’s manufacturer is also currently trialling a higher dose (7.2 mg). In the trial, patients on this 7.2 mg dose lost 20.7% of their starting body weight after 72 weeks. This higher dose may allow Wegovy’s effectiveness to reach the same average weight loss potential as Mounjaro.

Factors that Impact Effectiveness

There are many factors that can affect how much weight you will lose on each medication.

Side Effects

Some patients report experiencing worse side effects on Mounjaro. This means they may not tolerate the higher strengths. This will increase the time it takes to achieve the 22.5% weight loss.

Wegovy and Mounjaro share some common side effects, but the frequency and severity of side effects can vary. Some patients may find they are more likely to experience side effects on one medication over the other. But this seems to vary from patient to patient.

Side effects like nausea and vomiting can also make it hard to stay motivated to take these medications. It can also make it difficult to find the motivation to stay active and exercise. These are both core components of losing weight using Mounjaro and Wegovy.

Richard Wood, a pharmacist at Simple, says: “The ideal dose on either medication is the one where you feel supported but don’t have bad side effects.

“Not all patients reach the highest dose and that’s okay. Every journey is different and people can still achieve their goals on a lower strength.”

Diet and Lifestyle

Some patients will lose more weight because of other factors. For example, their levels of exercise and their history with weight loss. Patients who are more active will be more successful at managing their weight, regardless of which medication they use.

Patients who have used weight loss medications before may already have established healthy habits and mindset shifts. This can help them manage their weight when they switch to a new medication or return after a break.

How Long You Use the Medication

Building healthy habits is important for long-term weight maintenance. Staying on Mounjaro and Wegovy during the maintenance phase will allow you to manage your hunger while you create new habits and lifestyle changes.

You can use both Mounjaro and Wegovy to maintain your weight. There’s no limit to how long you can take it, as long as you still benefit from the medication.

When you stop using these medications, you may experience some “bounce back” and gain some weight. This is perfectly normal, and can occur with both medications. However, maintaining weight with the medications will help you establish habits to manage your weight in the long term, when you eventually come off it.

What Other Benefits Does Wegovy Have?

Both weight loss injections can help you lose weight, which can lower the risk of health problems like type-2 diabetes and high blood pressure. GLP-1 medications were originally developed to help people with type-2 diabetes manage their blood sugar levels. Aside from helping with this and losing weight, Wegovy has a few benefits over Mounjaro.

Clinical trials have shown that Wegovy can help reduce the risks of cardiac issues in overweight and obese patients who have previously suffered a major heart event, like a heart attack or stroke. The results also suggest the medication itself helps reduce the risks. This is independent of the benefits weight loss alone can have on reducing the risks of cardiac disease.

Wegovy also has the benefit of not affecting oral contraceptives when taken together. Mounjaro can reduce the absorption of the oral hormonal contraceptive pill, which can make it less effective. Wegovy also does not interfere with oral hormone replacement therapy (HRT).

Recent changes to the price of Mounjaro in the UK now mean Wegovy is more affordable for most patients. This can make it a much more attractive option for most patients, especially when they are choosing to maintain it long-term.

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Key Takeaways

Mounjaro and Wegovy Work in Similar Ways: They’re both GLP-1 receptor agonists, but they have different active ingredients. Mounjaro also works on another receptor in the body, called GIP.
Mounjaro Delivers Greater Weight Loss on Average: Patients lose around 22.5% compared to Wegovy’s 17%. Although individual results vary.
Lifestyle Changes Also Impact Effectiveness: Patients who make healthy lifestyle changes will see the best outcomes.
Wegovy Can Improve Heart Health: It reduces the risk of repeat cardiovascular events (heart attack, stroke) in overweight and obese patients.
Suitability Depends on Other Factors: Wegovy may be a better option for those using oral contraceptives. Or those with a history of heart disease.

References

Jastreboff, A.M., Aronne, L.J., Ahmad, N.N., Wharton, S., Connery, L., Alves, B., Kiyosue, A., Zhang, S., Liu, B., Bunck, M.C. and Stefanski, A. (2022). Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine, [online] 387(3). doi:https://doi.org/10.1056/nejmoa2206038.

‌Novo Nordisk. (2025). News Details. [online] Available at: https://www.novonordisk.com/content/nncorp/global/en/news-and-media/news-and-ir-materials/news-details.html?id=915087.

A. Michael Lincoff, Kirstine Brown‐Frandsen, Colhoun, H.M., Deanfield, J., Emerson, S.S., Sille Esbjerg, Søren Hardt‐Lindberg, G. Kees Hovingh, Kahn, S.E., Kushner, R.F., Ildiko Lingvay, Tuğçe Kalaycı Oral, Marie Mide Michelsen, Plutzky, J., Tornøe, C.W. and Ryan, D.H. (2023). Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. The New England Journal of Medicine, [online] 389(24). doi:https://doi.org/10.1056/nejmoa2307563.

Wilding, J.P.H., Batterham, R.L. and Calanna, S. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity. The New England Journal of Medicine, [online] 384(11), pp.989–1002. doi:https://doi.org/10.1056/NEJMoa2032183.

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