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Switching from Mounjaro to Wegovy, a guide

This guide explains how to safely switch from Mounjaro to Wegovy under GP supervision, a transition many are considering due to Mounjaro’s price hikes in the UK. 

By Rebecca Roberts Reviewed by Dr David Porter | Last updated Sep 30, 2025

This content is for information only and doesn't replace medical advice. Always consult your GP before starting weight loss injections to discuss suitability, risks, and monitoring. Seek medical attention if you experience concerning symptoms.
A woman measures her waist in the mirror

If you’re on a weight loss journey using Mounjaro, the thought of switching to Wegovy may have crossed your mind - especially with the price of Mounjaro tripling in the UK. The good news is, you’re not alone. Many Mumsnet users on our Talk boards are looking at their options for long-term weight management and are wondering whether a change to Wegovy is the right move. 

After all, making a switch between two medications can feel like a big step, but with the right information and support, you can make an informed choice that feels right for you and your health goals. 

We take a closer look at switching from Mounjaro to Wegovy, with the help of Dr Daniel Atkinson, Clinical Lead at Treated.com.

Why people are switching from Mounjaro to Wegovy

The main reason many people, including our very own Mumsnet users, are looking to switch their weight loss treatment is simple: cost. 

A recent price hike for Mounjaro has made it a less affordable option for some, prompting a search for a more budget-friendly alternative to treat obesity. 

Beyond the price tag, personal preference and side effects also play a part. Some find that one medication suits them better than the other. Since Wegovy has been around for longer specifically for weight management, it has a strong track record that many find reassuring. 

Discuss weight loss with fellow Mumsnet users

Mumsnet is the go-to destination for weight loss injection discussions. If you have any questions about weight loss injections and want to know about other people’s experiences of using them, head to our dedicated Talk board. 

Visit our weight loss injections board

How much is Mounjaro in the UK?

Let’s be honest, the recent Mounjaro price increase is a major factor as to why people are switching to Wegovy

Eli Lilly, the manufacturer, announced a list price increase in the UK from September 2025. So, for anyone trying to budget for their weight loss treatment, this sudden change has thrown a spanner in the works. 

But there's no way I'm going to be able to afford these new price increases, my only option is to change to Wegovy but then if everyone changes to Wegovy it will only be a matter of time before they increase those prices as well, then what happens?

ZoeSparkles

This increase means that continuing with your current medication could become much more expensive. When you're planning for long-term treatment to manage obesity, an unexpected price hike like the ones we’ve seen can make a huge difference to your monthly outgoings.

Here’s a quick look at the financial side of things:

  • Mounjaro (tirzepatide): The price has increased in September 2025, making it a more expensive option for many.

  • Wegovy (semaglutide): Often available at a lower price point, with more affordable long-term plans.

In short: if the cost of your treatment is a concern, Wegovy may present a more sustainable financial option for your weight loss journey without sacrificing effectiveness. 

If you’re receiving treatment via the NHS, speak to your GP. Due to a global shortage of Mounjaro recently, it may make sense for you to swap to Wegovy to ensure there’s no disruption to your treatment. 

Related: Are weight loss injections safe?

Do you need a new prescription for Wegovy?

In the UK, Wegovy is licensed for weight management whereas Mounjaro is licensed for both weight management and type 2 diabetes - so they're not exactly like-for-like. So yes, you absolutely need a new prescription to switch from Mounjaro to Wegovy. These are not interchangeable medications, and a medical professional must approve the change to ensure it's safe for you. 

The first step is usually to complete an online consultation where you'll answer questions about your health and your experience with Mounjaro.

A clinical team will then review your information to assess your suitability. This process is crucial for your safety and ensures the transition is managed correctly. They will look at your medical history, current dose, and any side effects you've had.

Once you’re approved, a prescription for Wegovy will be issued. The availability of these medications is generally good through private services, so getting access once you have a prescription is usually straightforward. The key is to go through the proper channels and get that all-important approval from a qualified prescriber.

A close up view of a Wegovy injection pen

You still need a prescription for Wegovy if you're switching from Mounjaro

Comparing Mounjaro and Wegovy

While both Mounjaro and Wegovy are weekly weight loss injections that help reduce appetite, there are some key differences to be aware of before you consider making a switch.

Let's look at how they work, what side effects you might expect and the kind of results they achieve.

What’s the difference between Mounjary vs Wegovy?

The primary difference between these two treatments lies in their active ingredient and how they function. 

  • Wegovy’s active ingredient is semaglutide, which mimics a single hormone called GLP-1 to help regulate your appetite and make you feel fuller for longer.

  • Mounjaro, on the other hand, contains tirzepatide. This is a dual-action ingredient that targets not only the GLP-1 receptor but also another one known as the GIP receptor. This dual mechanism is why Mounjaro is also effective for blood sugar control in people with type 2 diabetes, alongside its weight loss benefits.

Essentially, while both medications help you lose weight by affecting hunger signals, Mounjaro acts on two hormonal pathways compared to Wegovy’s one. 

This doesn't automatically make one better than the other; it just means they achieve similar results in slightly different ways.

Feature

Mounjaro

Wegovy

Active Ingredient

Tirzepatide

Semaglutide

Mechanism

Dual GIP and GLP-1 receptor agonist

GLP-1 receptor agonist

Primary Use

Weight management and blood sugar control

Primarily weight management

Common side effects between Mounjaro and Wegovy

When it comes to side effects, Mounjaro and Wegovy share a lot of similarities. Because they work in similar ways to slow down digestion and reduce appetite, the most common issues are gastrointestinal. You might experience some of these when you first start or when you increase your dose.

It's also possible to experience these side effects when switching from Mounjaro to Wegovy, as your body adjusts to the new medication. 

Many people find side effects improve over time, but for some they can be persistent. Managing them often involves simple dietary adjustments, like eating smaller meals and avoiding fatty foods. Do seek medical advice, however, if they don't improve.

Common side effects for both medications include:

  • Nausea

  • Diarrhoea

  • Constipation

  • Vomiting or stomach upset

If you've tolerated Mounjaro well, there's a good chance you'll do just fine on Wegovy, but it's always best to be prepared and speak to your clinician if you have any concerns.

Related: MedExpress reviews from Mumsnet users

What Mumsnet users say about switching from Mounjaro to Wegovy

“Me. I am only halfway through my weight loss journey and I cannot afford the higher prices. I have two pens in the fridge, once they are gone I will [be] switching, I just hope Wegovy works for me.” Deadringer

“I have toyed with the idea of the swap from [Mounjaro] due to the price increase also. I have done well on [Mounjaro]: 29lbs in nine weeks - the side effects haven’t been too bad either, just nightmares and fatigue some sickness… but now that my 7.5ml does is around £300 a month it’s just a sustainable cost for me at the moment.” BabyfoxesMama

“I’ve just taken my first dose of Wegovy today after seven months on Mounjaro. I’ve lost 4st in that time with only a stone to go until my target weight. I’ve had very few negative side effects on Mounjaro so I’m hoping I’ll be the same on Wegovy. I was on 10mg of Mounjaro and my pharmacy allowed me to start on 1mg of Wegovy. I was about ready to move up to 12.5 before the price increase.” Member218500

“I do get side effects on MJ and have considered swapping to see if I don't react so badly to Wegovy. But I'm actually doing well and losing weight on MJ, so I'm going to stay on it for the time being. And the four week period without drugs while changing also puts me off.” BerfyTigot

“I'm not sure I'll be able to afford it, but I'm wary [of switching] to Wegovy. Need to do some more research.” msbel2

A woman steps onto the scales, the camera is focused on her feet

Both drugs are effective tools for weight loss when combined with diet and exercise

What weight loss results to expect on Wegovy

A big question on anyone's mind is whether a new medication will be as effective. Clinical trials for both drugs have shown impressive weight loss results, though the numbers vary slightly. That said, it’s important to remember that these are averages, and individual results will always differ.

In trials, Mounjaro has shown an average weight loss of up to 20.9% of body weight at its highest dose. Wegovy is not far behind, with studies demonstrating an average weight loss of around 14.9%. However, newer data on higher Wegovy doses suggests it may achieve results closer to Mounjaro.

Ultimately, both are highly effective tools for losing a significant amount of weight when combined with diet and exercise. Switching to Wegovy doesn’t mean you should expect poorer results. 

For many, finding a medication they tolerate well and can afford long-term are the most important factors for achieving and maintaining their target body weight.

Related: Medicated weight loss, a complete guide

Getting ready to switch from Mounjaro to Wegovy

Before you make any changes, you'll need to go through a few checks. This involves making sure Wegovy is a safe and suitable option for you based on your health profile and your journey so far. 

Let's explore what's involved in checking your eligibility and what health factors need to be considered.

How to check if you’re eligible for Wegovy

The eligibility criteria for starting Wegovy are generally the same as for Mounjaro

To be prescribed this treatment for obesity, you typically need:

  • a BMI of 30 or higher

  • a BMI of 27 or higher if you also have a weight-related health condition like high blood pressure or type 2 diabetes

Can I switch if my BMI is below 27?

Possibly, yes. If you've already lost weight on Mounjaro and your BMI has dropped below 27, a prescriber may still approve the switch to Wegovy for weight maintenance.

Your clinical team will review your progress and medical history to decide if continuing a weight loss treatment is a safe and suitable option for you.

You can continue taking weight loss injections until your BMI is into the healthy range, so under 25. Many pharmacies will let you continue taking the injections as long as your weight doesn't get too low.

SilenceInside

If you've had significant success and stopping treatment could lead to regaining weight, continuing on a medication like Wegovy is often considered appropriate for weight maintenance. 

Your GP will review your progress and medical history to decide if it's a safe and suitable step for your ongoing care.

Health conditions to consider on Wegovy

When considering a switch, it's important to review your full medical history with your clinician. Wegovy might be a particularly good choice if you have certain health conditions. In fact, Wegovy is the only GLP-1 currently licensed in the UK to reduce cardiovascular risk in adults with overweight/obesity and established cardiovascular disease.

So if you have a history of heart disease, this added health benefit could be a significant reason to choose Wegovy. Studies have shown it can lower the risk of conditions like a heart attack or stroke in people with obesity and established cardiovascular disease.

You should always discuss your specific conditions with your prescriber. Some key points to consider include:

  • Heart disease: Wegovy has proven cardiovascular benefits.

  • Blood sugar control: Both medications are effective, but Mounjaro's dual action also targets GIP receptors, which are involved in glucose regulation.

  • Other conditions: Be sure to mention any other medical issues, as this will help your clinician determine the best course of action for you.

Find our full guide to Wegovy

What is Wegovy and how does it work? If you have questions about this GLP-1 receptor agonist medication, you’ll find everything you need to know in our complete Wegovy guide.

Learn more about Wegovy

Who should approach switching with extra caution

Dr Atkinson emphasises that switching medications requires careful consideration of your medical history: "If you've had side effects when using Mounjaro or another weight loss treatment before, like Saxenda or Nevolat, then switching to Wegovy should be approached with caution. 

“Make sure to tell your clinician about your experiences, so that they can recommend the dosing schedule that's right for you."

How to safely stop taking Mounjaro

Once your prescriber has given you the green light to switch, the process begins with stopping Mounjaro. You'll take your final Mounjaro dose as scheduled and then simply not take the next one. This is then followed by a planned waiting period before you begin your new medication. 

Let's look at the exact steps to take, what to expect during the break, and how long you need to wait.

Related: GLP-1 weight loss injections explained

Steps to take before stopping Mounjaro

You may wish to come off Mounjaro completely. If this is the case, speak to your GP before stopping your injections. 

If you’d prefer to switch to Wegovy, do not stop taking your medication until they have confirmed that switching to Wegovy is a safe and appropriate choice for you.

Once the switch is approved, the process is quite simple. You will take your last Mounjaro dose on your usual injection day. After that, you just need to wait for the recommended period before starting Wegovy. There’s no need to do anything else to “clear” the medication from your system; time will do the work.

Here’s a summary of the steps:

  • Get confirmation from your clinical team to make the switch.

  • Take your final scheduled dose of Mounjaro.

  • Wait for the recommended washout period to pass before starting your new medication.

Do you get withdrawal symptoms after stopping Mounjaro?

The term "withdrawal symptoms" can sound a bit scary, but when stopping Mounjaro, it's not what you might think. You are unlikely to experience any unpleasant symptoms coming off Mounjaro.

Instead, the most noticeable change during the brief pause between medications will likely be a return of your appetite.

As the effects of Mounjaro wear off during the seven-day break, you might feel hungrier or notice an increase in food cravings. This is perfectly normal and expected. Any side effects you were experiencing from Mounjaro, like nausea, should also settle down during this time.

The key is to be prepared for this temporary increase in appetite. Sticking to the healthy habits you've already built will provide great support during the transition.

Dr Atkinson recommends practical preparation for managing increased appetite: "It can help to draw up a meal plan beforehand, and cook healthy meals in advance and store them in the freezer. Having meals ready and prepared means you won't be as tempted to buy something less healthy in the spur of the moment."

He also suggests stocking up on healthy snacks: "Make sure you've got plenty of healthy snacks in stock too – unsalted nuts like cashews or walnuts, and fruit. If you've got these available, you're less likely to reach for an unhealthy option."

If you feel unwell or have any concerns, don't hesitate to reach out to your clinical team for advice.

Is it safe to switch from Mounjaro to Wegovy without medical support?

No, it is not safe to switch without medical support. The process requires guidance from a clinical team or prescriber to ensure your safety. They will determine the correct dosage and manage the transition to minimise risks and maintain the effectiveness of your treatment. 

Never attempt to switch on your own.

How long to wait before starting Wegovy

While there's currently no official guidance on switching between these medications, Dr Daniel Atkinson, Clinical Lead at Treated.com, explains the safest approaches: "The most entirely risk-free, 'by-the-book' way to do it would be to wait a month for the drug in Mounjaro to completely leave your system, then start your new treatment with Wegovy from the lowest dose."

However, for most people who have been tolerating Mounjaro well, a shorter transition may be appropriate. "It's more likely that your clinician would advise you to wait two weeks if Mounjaro had been working well for you, and not causing any significant side effects," says Dr Atkinson.

This brief pause is often called a "washout period," and it allows enough of the Mounjaro to leave your system, which helps reduce the risk of overlapping side effects when you start the new medication. Taking both too close together could increase the chances of feeling unwell with symptoms like nausea or stomach upset.

Your GP will confirm this timing with you. For example, if your last Mounjaro injection was on a Monday, you would take your first Wegovy injection when advised by your GP. This ensures a smooth transition and helps you get started on your new treatment safely.

A woman injecting herself with weight loss medication

Discuss when you should start Wegovy following Mounjaro with your GP

What’s the right Wegovy dose after taking Mounjaro?

After switching from Mounjaro, it’s not like you’re starting from scratch. Your previous experience with the medication will inform your new Wegovy treatment plan - particularly your initial dosage. 

When you switch to Wegovy, you won't automatically start on the lowest dose of 0.25 mg. 

Dr Atkinson explains that dosing decisions are highly individual: "Switching treatment is an individual thing really, and depends on your response to the treatment, and how far along in your weight loss journey you are - your clinician will be able to give you tailored advice."

As an example, he notes: "If you were taking 10mg of Mounjaro, a clinician might advise starting Wegovy but dropping to the 1mg or 1.7mg dose, with a view to moving up to 2.4mg after a couple of months."

From there, you'll likely follow the standard Wegovy schedule, gradually increasing your dose every four weeks until you reach a maintenance dose that works for you. 

Related: Can you get weight loss injections on the NHS?

Wegovy dosing compared to Mounjaro

You can't do a direct mg-for-mg switch between these medications because they are different drugs with different strengths. A 5 mg Mounjaro dose is not equivalent to a 5 mg Wegovy dose. Instead, clinicians use a dose conversion guide to find a suitable starting point.

This conversion ensures you begin on a Wegovy dose that is effective but not overpowering. If you've had issues with side effects on a higher dose of Mounjaro, they might suggest starting on a lower dose of Wegovy to ease you in gently.

The table below gives an example of how a typical dose conversion might look. 

Current Mounjaro dose

Recommended starting Wegovy dose

2.5 mg

0.25 mg

5 mg

0.5 mg

7.5 mg

1 mg

10 mg

1.7 mg

12.5 mg

1.7 mg

15 mg

1.7 mg

Please note: These are example conversions only. Dr Daniel Atkinson advises that your clinician may recommend starting at a lower dose than shown here, depending on your individual response to treatment and how far along you are in your weight loss journey.

Managing side effects after moving to Wegovy

If you do experience side effects like nausea, constipation, or diarrhoea when you start Wegovy, don't worry. There are simple ways to manage them, and they usually improve as your body adjusts. The key is to be gentle with your digestive system.

Sticking to smaller, more frequent meals can help prevent feeling overly full or nauseous. It’s also wise to limit high-fat, spicy, or very sugary foods, as these can often trigger or worsen symptoms. Staying well-hydrated by drinking plenty of water throughout the day is also incredibly helpful.

Here are a few tips that many people find useful:

  • Eat bland foods like crackers or toast if you feel nauseous.

  • For constipation, increase your fibre intake and stay active.

  • Avoid alcohol and caffeine, as they can exacerbate digestive issues.

If your side effects are persistent or severe, always speak with your clinical team.

Related: Ozempic vs Mounjaro vs Wegovy - which one is best for weight loss?

Will changing to Wegovy affect weight loss goals?

It's natural to worry that a change in medication could derail your weight loss goals. 

However, switching to Wegovy doesn't have to mean a setback. In fact, for some, it can be a positive step forward, especially if cost or side effects were becoming a barrier with Mounjaro.

My experience so far has been pretty steady all round. A bit of nausea the day after I inject and a bit of constipation [...]

CagneyNYPD1

The transition period is key, and with the right approach, you can keep your weight management journey on track. 

Will I gain weight when switching from Mounjaro to Wegovy?

It’s unlikely you’ll gain significant weight. You might notice a small, temporary increase during the seven-day break as your appetite returns, but this usually reverses once you start Wegovy. 

Sticking to your healthy habits during the transition will help you continue your weight loss progress without any major setbacks.

Join the conversation

Start a new discussion about your experience of Wegovy and get support from the Mumsnet community.

Can you switch from Mounjaro to Wegovy on the NHS?

Access to weight loss injections like Wegovy in the UK is available through both the NHS and private providers. However, the criteria for NHS access are very strict and waiting lists can be long. 

With that said, if you’re experiencing side effects on Mounjaro and wish to move to Wegovy - and you meet the NHS eligibility criteria - there’s no reason why you shouldn’t be able to switch. On the NHS, both Wegovy and Mounjaro are normally limited to a maximum of two years in specialist weight management services, with six-monthly reviews.

Private services, often through an online consultation with a registered pharmacy, offer a much quicker route to getting a prescription. You can complete an assessment from home, and if you're eligible, the medication is delivered directly to you. This convenience is a huge plus for busy parents.

Here’s a quick summary of your options:

  • NHS: Strict eligibility criteria and may involve long waits for specialist weight management services.

  • Private: Faster access via online consultations with regulated providers and pharmacies.

  • Cost: NHS prescriptions are cheaper, but private access is more readily available, with Wegovy now a more affordable private option than Mounjaro.

Useful links for more information

🔎 This article has been medically reviewed

Last reviewed in September 2025 by Dr David Porter MBBS, MSc, PgDip, an internationally renowned sports medicine physician and Founding Director of Opus.

Learn more

About the expert

  • Dr Daniel Atkinson is the Clinical Lead at Treated.com, an online healthcare service company.

About the author

Our resident Leeds lass, Rebecca Roberts is a Senior Content Editor here at Mumsnet. On a daily basis, she commissions, writes and edits content designed to help parents navigate real life - from product reviews to practical features on everything from sex and relationships to fashion to skincare.

Rebecca - aka Beccy - brings unique personal insight to weight loss content here at Mumsnet, having undergone her own journey with medically supervised injections. Her firsthand experience with GLP-1 treatments provides authentic expertise that resonates with parents exploring similar options. 

Beyond her role as an editor, she can be found balancing life as a working mum of two toddlers and when she’s not at her desk, you’ll likely find her at a PTA meeting, in a nearby coffee shop, or walking her two dogs up and down country lanes.

Read more: Weight loss injections - should you consider them?