Mounjaro vs Wegovy: What's best for you?

If you’ve been keeping an ear to the ground in the world of weight-loss medication, two names have probably been cropping up again and again: Mounjaro and Wegovy. Both are weekly injections, both have been shown to help with significant weight loss, and both have their own devoted fans. But how do they actually compare?

Let’s break it down—without the medical jargon overload—and see where each one shines.

How They Work

Wegovy contains semaglutide, which is what’s known as a GLP-1 receptor agonist. In plain English, that means it mimics a natural hormone in your body that helps regulate your appetite and blood sugar levels. The result? You tend to feel fuller sooner, and that can make it easier to eat less without constantly thinking about food.

Mounjaro, on the other hand, uses tirzepatide, and here’s where it gets interesting. Instead of working on just one hormone pathway like Wegovy, it acts on two—GLP-1 and GIP receptors. That dual action may give it an extra edge in controlling appetite and improving the way your body handles blood sugar.

Both are weekly injections you can self-administer at home, but the dosing is slightly different. Wegovy starts low at 0.25 mg and gradually works up to a steady 2.4 mg maintenance dose. Mounjaro also starts low—2.5 mg in most cases—but offers a range of maintenance doses (5 mg, 10 mg, or 15 mg). That flexibility can be useful for finding the balance between results and side effects.

Side Effects and Tolerability

Because they work in similar ways, the side effects are also pretty similar. The most common ones are nausea, vomiting, diarrhoea and sometimes constipation, especially while your body is adjusting to a higher dose. In earlier studies, slightly more people stopped taking Mounjaro because of side effects compared with Wegovy, but in the most recent trials, that difference was smaller. Either way, starting low and going slow with dose increases tends to help for both medications.

Which Works Better?

Here’s where the head-to-head data comes in. In the SURMOUNT-5 study published earlier this year, researchers directly compared the two drugs over a period of 72 weeks. On average, people taking Mounjaro lost about 20% of their body weight, while those on Wegovy lost around 13–14%. In real-world terms, that’s roughly 23 kg lost with Mounjaro versus 15 kg with Wegovy. That’s a pretty clear difference, although it’s worth noting that both drugs led to clinically significant weight loss for most participants.

Here's where things start to get really interesting, though. Yes, Mounjaro is the winner on average when talking about amount of weight lost. But a recent announcement from Eli Lilly, the drug's manufacturer, noted that the cost is about to significantly rise throughout the UK - and it was already the higher priced of the two medications. This makes Wegovy's 13-14% weight loss a lot more appealing to many consumers.

The Strengths of Each

If your main goal is to achieve the largest possible weight loss—and you can tolerate the medication well—Mounjaro currently has the stronger evidence. Its dual-hormone action seems to give it that extra push, and it offers multiple dose options to suit different needs.

Wegovy’s strengths lie in its simplicity and track record (as well as that price tag we mentioned earlier). It’s been in use longer, has official approval for heart-risk reduction as well as weight loss, and the dosing routine is easy to follow once you’ve built up to the full amount.

So… Which Should You Choose?

Honestly, there’s no one-size-fits-all answer. Some people respond better to one medication than the other, and tolerability can play a big role in deciding. The good news is that both have strong clinical backing, and both can be life-changing when used alongside healthy eating, physical activity and ongoing medical guidance.

And that’s the key point—they’re tools, not magic wands. Whichever path you choose, it works best when it’s part of a broader plan to look after your health long-term.

This is where we come in! At MSH Weight Loss, we offer both as viable options for weight loss, and we can help you understand and get started down the path that's right for you - and even change course if you need to. Get in touch by starting your assessment here or contacting us today!