Have you been using Wegovy but are thinking of switching it up? Perhaps you’ve not seen the results you hoped for—or you read that Mounjaro works better for weight loss.
Changing from Wegovy to Mounjaro is definitely doable if that’s the right thing for you. But it’s not as simple as swapping one injection out for another. Mounjaro and Wegovy may be similar, but they’re separate medicines that each work in their own way. And they both come with their own set of instructions around dosing.
If that sounds like a lot to get your head around, don’t worry—we’re here to explain everything you need to know about making the switch.
What are Wegovy and Mounjaro?
They’re both weekly injections for weight loss that are used alongside changes to diet and exercise. Each is more effective than lifestyle adjustments alone and works by making you feel full.
But they go about this in distinct ways. This is because Mounjaro and Wegovy have different active ingredients, which is what makes a medicine work.
Wegovy uses semaglutide, which behaves like the hunger hormone GLP-1. It works to suppress appetite via a range of actions. It communicates directly with the brain to suppress appetite and reduce cravings, helping to dampen down 'food noise', and it slows down digestion so we feel fuller for longer.
With Mounjaro, the active ingredient is tirzepatide. It acts like GLP-1 but also another hormone called GIP. Tirzepatide dials down our appetite and regulates our insulin levels in the same ways that semaglutide does, but it does so via the effects of two hormones rather than one.
For this reason, Mounjaro is considered more effective than Wegovy.
Why switch from Wegovy to Mounjaro?
There’s plenty of reasons why someone might want to swap from Wegovy to Mounjaro.
You’ve heard that Mounjaro is more effective
That’s what the research says. In one analysis of over 40,000 health records, people taking Mounjaro lost an average of 15.3% body weight after a year compared to 8.3% for those on Wegovy.
But watch out: scientific research reports average results from lots of people. This can’t tell you how a medicine will affect you personally. So, we can’t say for sure whether you’d be better off on Mounjaro.
Wegovy isn’t working as you hoped
It happens—not everyone taking weight loss medication sees the results they want. If you’ve been using Wegovy but it’s not working as well as expected, or perhaps you’ve reached a plateau in your progress, you might like to try something new.
You’re having side effects while using Wegovy
Both Wegovy and Mounjaro bring on similar side effects. But, as we’ve mentioned, they are two separate medicines and it’s possible that they’ll affect you differently. Mounjaro might be an option if Wegovy is bringing on symptoms that are bothering you.
You’re having trouble getting Wegovy
As demand for these medicines rises, there’s a risk they’ll become short in supply. It’s something that’s already happened in the UK for Wegovy. If one weight loss medicine becomes unavailable, it’s understandable that people would want to switch to another.
Wegovy is more expensive
Based on the current UK list prices, Wegovy is the dearer medicine. For the highest dose, it’s £175.80 per pack, compared to £122 for Mounjaro (though if you access these medicines through a private provider, the costs may be different).
How to switch from Wegovy to Mounjaro
Wegovy and Mounjaro aren’t interchangeable: you can’t just replace semaglutide with tirzepatide from one week to the next. And you definitely shouldn’t use them both at the same time.
If you want to make the change, please make sure you do it safely.
1. Speak to your doctor
They should be your first port of call when looking to switch up your medicine. Tell them you’re interested in trying Mounjaro and why. When (and only when!) they give the all-clear, you can move to the next step.
2. Take your last dose of Wegovy
Your doctor will confirm when you can take your last dose. After you’ve done it, safely dispose of the pen per the advice in the leaflet that came with it.
3. Wait at least a week
Wegovy has a half-life of seven days, which means that it takes a week for half of the medicine you took to leave your system. At that point, there’s not enough of it left to work as it’s supposed to. Again, your prescriber will tell you how long you should wait before taking Mounjaro.
FYI: it will take about 5 weeks for Wegovy to completely leave your system.
4. Start on a low dose of Mounjaro
Even if you were on the highest strength of Wegovy, you’ll have to follow the dosing guidance for Mounjaro when you take it. As there is no direct dose conversion between Wegovy and Mounjaro, you would have to start at the lowest dose of 2.5mg.
Who can switch from Wegovy to Mounjaro?
Whether it’s okay for you to try Mounjaro is up to your doctor. They’ll consider your medical history and where your health is at right now when making the call.
Like Wegovy, Mounjaro is recommended for people with a BMI of 30 or more. It isn’t meant for people who are pregnant, breastfeeding, or have type 1 diabetes.
And when you have the conversation about switching medicines, tell your doctor about your current and past medical conditions and any medications you are taking.
How to stop Wegovy
We know we’re repeating ourselves here, but just to hammer this home: speak with your doctor first before stopping Wegovy. They’ll confirm when you should take your last dose and how long you need to wait before trying Mounjaro.
When you stop taking a medicine, it gradually gets flushed out of your system. We’ve already mentioned that it takes a week for half a dose of Wegovy to clear out. So, at around that point, its effects will start to wind down.
Making the switch
Trying something to improve your health, only to have it not work out as you’d hoped, can definitely be disheartening. But if one medicine isn’t working for you, another might. And as they say: nothing good ever came easy.
That’s certainly true when it comes to losing weight. For best results, it’s a process you need to stick with for at least a year. That means making lasting, healthy changes to your habits.
So, if you’re wanting to move from Wegovy to Mounjaro, we’ll be right here in your corner, supporting you all the way. Through our weight loss programme, you can get guidance and advice from our team of experts plus access to weekly medication. And you can keep tabs on your progress via an app. You can get started right now: fill out this form to see if the programme is a fit for you.
FAQs
What are the side effects after switching from Wegovy to Mounjaro?
Side effects are fairly common when using Mounjaro, but they’re usually mild and clear up on their own or can be managed with self-care measures and over-the-counter remedies. The most common symptoms are nausea, diarrhoea, vomiting, and constipation—which may affect up to one in ten people. If your side effects persist or worsen, contact your clinician for further support.
Can you switch from Wegovy to a different dose of Mounjaro?
No, please don’t do this. Wegovy and Mounjaro are different medicines. They each have their own guidance around dosing which is based on our understanding of their safety. When you start taking Mounjaro, you should follow its dosing schedule to reduce your risk of side effects.
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