Switching from Mounjaro® to Wegovy®
Mounjaro® is a proven option for weight management, but it is not suitable for everyone. Rising treatment costs in the UK and recent price increases have caused concern for some patients, while others find the medicine difficult to tolerate.
Why switch from Mounjaro® to Wegovy®?
There are few different reasons why someone who is currently taking Mounjaro® might want to change to Wegovy®, including:
The cost difference of the two medications
Slower progress than expected
The side effects experienced
Everyone is different and some people simply find that their body doesn’t respond as well as they’d hoped to Mounjaro®, or they find that they experience some side effects that are difficult to live with. While the two medications have some similarities, they do work in slightly different ways.
Both Wegovy and Mounjaro are weekly injectable treatments that act on the body in similar ways. Wegovy’s active ingredient is semaglutide, while Mounjaro contains tirzepatide.
Is Wegovy® as effective as Mounjaro in the long term?
Clinical trial data shows that Mounjaro® leads to greater average weight loss compared with Wegovy®. As of July 2025, Mounjaro® remains the most effective licensed medicine for weight management.
Wegovy® is still a highly effective treatment and provides significant, lasting weight loss. At the maximum approved dose (2.4 mg), patients lost an average of about 15% of their body weight over 68 weeks, with around 10% loss by 6 months. This is substantially more than most people achieve with lifestyle changes or older medications alone.
A higher-dose version of Wegovy® (7.2 mg) is expected to launch later in 2025. In trials, patients taking this dose achieved an average weight loss of 21%, with about one in three losing 25% or more. Side effects were similar to those reported at 2.4 mg.
Other benefits of Wegovy® include:
Support for heart health
No impact on oral contraceptive effectiveness
Lower cost compared with Mounjaro®
Switching from Mounjaro® to Wegovy®: Dosage changes
When switching from Mounjaro® to Wegovy®, it’s likely to mean that a dosage change is needed to minimise any side effects from the new medication. The specific starting dose for Wegovy® may or may not be the minimum of 0.5mg, as this will depend on the Mounjaro® dose you were taking and your medication tolerance experiences so far on your weight loss journey. It’s important to take the recommended starting dose to reduce the risk of side effects while your body gets accustomed to Wegovy®.
View PillTime’s dosage advice for those switching from Mounjaro® to Wegovy®:
Mounjaro® dose
2.5
5
7.5
10
12.5
15
Wegovy dose®
0.25
0.5
1.0
1.0
1.7
1.7
How Mounjaro® and Wegovy® are different
Mounjaro® (tirzepatide) and Wegovy® (semaglutide) are both medications known as GLP-1 receptor agonists. This means that they mimic the hormone GLP-1 (glucagon-like-peptide-1), which sends the brain messages saying that the individual feels full. This type of medication also slows down the rate at which food leaves the stomach. So, not only does the person taking it feel full after eating less food, they stay feeling full for longer.
The main difference between Mounjaro® and Wegovy® is that Mounjaro® also mimics another hormone (GIP – glucose-dependent insulinotropic polypeptide), which can have a stronger effect on some people and can also support diabetes management.
However, stronger results can come with trade-offs. Some patients experience more side effects on Mounjaro®, and the cost is substantially higher. The manufacturer, Eli Lilly, has announced a 170% price rise for September 2025.
Wegovy® is currently the only weight loss injection that is proven and licensed to be used to reduce the risk of cardiac health problems, such as strokes or heart attacks.
How to switch from Mounjaro® to Wegovy® safely
It is often possible for people to switch from Mounjaro® to Wegovy®, but it’s important that this is done under medical supervision to ensure that the transition is suitable for your individual health profile.
You will need to ensure that you are eligible for a Wegovy® prescription and the switch itself needs to be managed carefully to minimise side effects.
There needs to be a short break of at least seven days after the previous dose of Mounjaro® was taken before the first dose of Wegovy® is delivered. This is sometimes called a ‘washout’ period. This is to stop the two medications from overlapping in the body, which can increase the risk of negative side effects.
The first dose of Wegovy® after previously taking Mounjaro® will also be a different dosage to the other medication, so it’s essential that this is managed clinically to help the body tolerate the change.
How to switch from Mounjaro® to Wegovy® with PillTime
If you are already a PillTime customer for Mounjaro®, you can simply use our online support services to get in touch with your request and we will discuss your options with you, including assessing if you are suitable for switching to Wegovy®.
If you are a new customer to PillTime, you can take our weight loss medication assessment to determine if you are eligible for Wegovy® and if so, our pharmacy team will arrange your prescription.
A clinician from our team may reach out to you to confirm a few details, to ensure the switch is safe and tailored to you. You'll get ongoing check-ins during the first month of your switch, but our clinical and customer care teams will be here beyond that to support you throughout your weight loss journey.
Tips for a smooth transition from Mounjaro® to Wegovy®
Stick to your weekly injections and try not to miss doses.
Make a note of any side effects and discuss them with your healthcare provider.
Take a long-term view. Gradual, steady weight loss is usually safest and most sustainable.
Support your treatment with healthy habits around diet, physical activity, and sleep.
What to expect after switching from Mounjaro® to Wegovy®
Will I experience the same side effects on Wegovy® as I did on Mounjaro®?
Wegovy® and Mounjaro® act in similar ways, so they may cause similar side effects. If you tolerated Mounjaro® well, you are less likely to develop new or worse side effects when moving to an equivalent dose of Wegovy®.
The most common side effects include:
Nausea
Vomiting
Diarrhoea
Constipation
Stomach pain
Wegovy® may also cause fatigue or headaches in some people. These effects are usually mild and temporary, and in some cases may be related to dehydration or not eating enough nutrient-rich foods.
Your healthcare provider can help plan a safe transition to Wegovy®, aiming to maintain effectiveness while reducing the risk of side effects.
If you would like further guidance on managing side effects, you can visit PillTime help.
Will I have to begin again on the lowest Wegovy® dose?
In most cases, no. The dose you start with is influenced by the strength of Mounjaro® you were last taking and the length of time you had been using it. Your clinician will advise the most appropriate entry point.
Sometimes it is safer to introduce Wegovy® at a lower dose. This approach is designed to limit side effects and allow your body to adjust gradually. It should be seen as a protective step rather than a loss of progress.
The overall aim is to continue weight loss in a way that is consistent, manageable, and well-tolerated over the long term.
On a practical level, taking both medications is very similar, with a weekly self-delivered injection. One difference is that your Wegovy® pen will not need priming before every use, only before the first injection from each pen. Mounjaro® needs to be primed before every dose.
In terms of weight loss, everyone’s experience can be unique when switching from Mounjaro® to Wegovy®. Some people may find that they continue to lose weight at a similar rate or faster to when on the previous medication and some may experience more of a plateau while their dosage is gradually increased over time.
The important thing when making the switch is to follow your clinician’s specific instructions to keep the changes as safe as possible.
Weight Loss Injections
Why Choose PillTime?
As an NHS-registered pharmacy with 13,000+ 5-star Trustpilot reviews, you’re in safe hands.
Ongoing assessment by a registered prescriber to support your weight loss journey.
Your medication is tracked and delivered discreetly by Royal Mail.
FAQs on switching from Mounjaro® to Wegovy®
Can you start Wegovy® after Mounjaro®?
Yes, it is possible to move from Mounjaro® to Wegovy®. To do this safely, a one-week gap (sometimes called a washout period) is required between stopping Mounjaro® and beginning Wegovy®.
This short break allows your body time to reset and helps reduce the risk of side effects when starting the new medication.
Do I need a new prescription to make the switch?
As Mounjaro® and Wegovy® are different medications, you will need a new prescription to be arranged before you can start taking Wegovy®.
Is it safe to swap Mounjaro® for Wegovy®?
It is considered safe to stop taking Mounjaro® and start taking Wegovy® as long as you follow your prescriber’s specific instructions on doing so. This means leaving at least seven days between your final dose of Mounjaro® and your first dose of Wegovy® and taking the prescribed dose only.
Will there be withdrawal symptoms when I stop taking Mounjaro®?
Mounjaro® is not a medication that will cause withdrawal symptoms when you stop taking it. As the medication wears off, some people may notice a slight increase in their appetite.
Will I put weight on while switching from Mounjaro® to Wegovy®?
Changing from Mounjaro® to Wegovy® does not usually mean starting over. Because both medicines work in similar ways, your prescriber can often align your new Wegovy® dose with the level of treatment you had already reached on Mounjaro®. This helps maintain momentum without needing to return to the very first dose.
Most people continue to lose weight after the switch, though the rate may vary. Some may notice a temporary slowdown, while others progress at a similar pace. Regaining weight during this transition is uncommon, provided the treatment is taken consistently.
Regular monitoring and follow-up support ensure any adjustments can be made quickly, helping you stay on track with your long-term goals.
