Switching from Mounjaro to Wegovy 

You can switch from Mounjaro to Wegovy if your pharmacist thinks it’s safe and suitable for you.  You will usually need to wait at least seven days between your last dose of Mounjaro and your first dose of Wegovy. You will also need to adjust your dosage depending on what dose of Mounjaro you were previously taking. 

In this article, we cover what to expect when switching from Mounjaro to Wegovy so you can continue your weight-loss journey safely with the treatment that is best for you. 

This guide is intended to give you enough information to make an informed choice about your weight loss journey but if you have any concerns speak to your pharmacist or health care provider. 

Key take aways:

• Both weight loss injection medications are part of a group called GLP-1 receptor agonists, which work in a similar way to help you lose weight by reducing appetite and slowing down how quickly your stomach empties. Mounjaro also targets GIP receptors, which means it can support both weight loss and diabetes management

•  You can switch between the two treatments after a short break between your final Mounjaro dose and your first Wegovy dose. Your new starting dose will be adjusted to help reduce side effects while still supporting your weight loss

• Switching is always your choice, but it does need to be approved by our clinical team. While Wegovy is generally the less expensive option, you may also want to switch because of side effects or just personal preference. Studies have shown that both treatments are safe, effective, and help patients achieve similar weight loss results

How to switch from Mounjaro to Wegovy

• Request Wegovy by completing an online consultation 
• Our clinical team will assess if you can safely switch 
• If you are eligible, we will issue your Wegovy prescription  
• You must then stop taking Mounjaro 
• Wait at least seven days for the medication to washout of your system 
• We will deliver your prescription discretely packaged to your door - make sure you keep it in the fridge 
• Start using your new medication and continue your weight loss journey

Am I eligible for Wegovy? 

If you’ve never taken a weight loss injection before, Wegovy has the same eligibility criteria as Mounjaro. This means you are likely to be approved for Wegovy if you have: 

• a BMI of 30 or higher 

• a BMI of 27 or higher if you also have a pre-existing medical condition that is affected by your weight, such as cardiovascular disease or high blood pressure 

If you’ve already lost weight while taking Mounjaro, and are now below the eligibility criteria, you may still be able to switch, as long as a pharmacist approves it. In this case, Wegovy can be prescribed as part of your ongoing weight loss maintenance plan. 

Can I switch to Wegovy if my BMI is below 27?

Possibly. If you already take Mounjaro and have lost weight, or you are using it to maintain your target weight, you may still be able to switch to Wegovy. Our clinical team will review your medical history and decide if it is safe and suitable for you. 

How do I stop taking Mounjaro?

Do not stop Mounjaro until our pharmacists or your prescriber confirms the switch to Wegovy is possible. When approved, or if you've already taken your last dose, wait at least seven days before starting Wegovy. You do not need to do anything else — just do not take another dose of Mounjaro. 

How do I start taking Wegovy?

Start Wegovy at least 7 days after your last Mounjaro dose, at the dose your prescriber recommends. Use the once-weekly pre-filled pen and inject into your tummy, thigh, or upper arm on the same day each week. For pictures and full steps, see our injection guide.

Do I need to start on the lowest dose of Wegovy if I switch? 

Your starting dose will depend on the dose you were taking while on Mounjaro. 

Here’s what a typical dosing schedule looks like when switching from Mounjaro to Wegovy for each dose: 

Important: Your pharmacist will review your health and your experience with Mounjaro when setting your starting dose. This helps to minimise side effects while ensuring you can safely maintain your weight loss during the switch.  

Are there any differences when changing treatments? 

There are a few small differences you’ll notice when switching treatments, but for the most part Wegovy and Mounjaro are very similar medications.  

Differences to keep in mind: 

Priming your pen 

Wegovy does not require priming before every dose. You only need to prime the pen before taking your first injection. For all following injections from the same pen, you do not need to. This is different to Mounjaro, which requires priming before every injection. 

Storage 

Both treatments must be refrigerated until their first use. Once opened, Mounjaro can be kept at room temperature (up to 30°C) for 30 days, but Wegovy can only be stored at room temperature for up to 42 days. 

Is it safe to switch from Mounjaro to Wegovy after a seven-day break? 

It’s often considered safe to switch from Mounjaro to Wegovy after a short wash out period because: 

• Both treatments work on the GLP-1 receptor. Mounjaro also targets GIP receptors. This means the medications affect your body in very similar ways, which can make switching between them more tolerable. 

• When you stop taking Mounjaro, its effects on GIP receptors gradually reduce and fade, as Wegovy does not act on these receptors. 

• Most people find that a seven-day gap between their final dose of Mounjaro and their first dose of Wegovy is enough to reduce the risk of overlapping side effects, such as bloating and nausea. 

• There’s no conflict between how Mounjaro and Wegovy work in the body, so there’s very little chance of them reacting with each other. Both also stay in your system for a long time. This is called a “long half-life.” A half-life is the time it takes for half of a medicine to leave your body. 

Since Mounjaro and Wegovy act in very similar ways, with similar ingredients and half-lives, switching between them is considered safe and effective, as long as it’s done under the supervision of a medical professional. 

Chemist4U Head of Pharmacy and Clinical Lead Jason Murphy, cautions: Please note that the manufacturer recommends leaving 30 days from your last dose of Mounjaro and your first dose of Wegovy, to further reduce the risk of side effects, however we understand this could result in stalling your weight loss journey or potential weight gain.  

Why should I consider switching? 

There are a few reasons you may want to switch to Wegovy from Mounjaro, but ultimately, it’s about what works best for your health and weight loss journey. 

Side effects & how you tolerate it 

People respond to medications in different ways, and even though Mounjaro and Wegovy share similar ingredients, you may tolerate one better than the other. Some patients report experiencing milder side effects with Wegovy, making it a better choice for their journey. 

If your current treatment is causing symptoms such as nausea, diarrhoea, constipation, or vomiting, and these become difficult to manage in your daily life, it may be worth considering a switch, as you could find the other medication easier to live with. 

Progress and effectiveness 

During your weight loss journey, you may notice that your progress slows down or that you stop losing weight. This is known as a weight loss plateau, and it’s a normal part of the process as your body adjusts to changes in diet and medication. In most cases, weight loss will start again fairly quickly, but sometimes you may need to adjust your diet or review your dosage. 

If your progress continues to slow over a longer period, it may be due to how your body is responding to treatment. In this case, making a change could help, as you might respond better to a different medication. 

Recent clinical trials for Wegovy have shown promising results, with patients losing up to 20.7% of their body weight. In fact, three patients in the study lost 25% or more. These outcomes are much closer to the results typically seen with Mounjaro, helping to close the gap between the effectiveness of these treatments. 

Additional health benefits (Cardiovascular) 

Right now, Wegovy is the only weight loss injection proven and licensed to be used to reduce the risk of cardiac health problems, such as strokes and heart attacks, in people with obesity and heart disease. This has been demonstrated in clinical trials. 

Mounjaro has shown some promising similarities in helping people with these conditions, but it is not licensed to do so. 

Contraception 

Wegovy does not interfere with oral contraception, so you can focus on your weight loss journey without changing your contraceptives or worrying about risk of pregnancy. Learn more about how weight loss injections interact with contraception. 

Will I experience side effects when switching from Mounjaro to Wegovy?

There is a chance you’ll experience side effects when switching from Mounjaro to Wegovy. The longer you wait between your last dose of Mounjaro and your first dose of Wegovy, the more reduced your chances of side effects are. If you switch after 1 week since your last dose of Mounjaro, there will still be Mounjaro in your system, which can lead to side effects like, nausea, diarrheoa and constipation. Your pharmacist will help set your Wegovy dose to reduce side effects and make the switch easier. 

Since both weight loss injections work similarly, most people transition smoothly with minimal side effects. You might experience mild nausea or stomach upset for one to two weeks as your body adjusts, though some people notice no difference.  

If you've tolerated Mounjaro well, you'll likely do fine on Wegovy. Your prescriber may start you on a low dose and increase gradually to minimise any side effects. 

Frequently asked questions answered by Chemist4U Head of Pharmacy, Jason Murphy: 

Can I switch back to Mounjaro after switching to Wegovy?

Yes. You can, but there's a longer period in between stopping Wegovy and starting Mounjaro, and you will need to restart on a lower dose. Learn more about switching to Mounjaro.

Is it safe to switch from Mounjaro to Wegovy?

Yes. It’s considered safe to switch from Mounjaro to Wegovy as long as you’re following your prescriber’s instructions on how to do so. This means leaving at least seven days between your final Mounjaro dose and first Wegovy dose, and ensuring Wegovy is safe and suitable for you to take. 

Will I experience withdrawal when I stop taking Mounjaro?

There are no “withdrawal” symptoms in the usual sense. Some people notice their appetite increases as the medicine wears off, and any side effects usually settle after stopping. If you feel unwell or are unsure what to expect, speak to our pharmacists. 

If I switch to Wegovy, do I need to start from the lowest dose?

If you’re switching to Wegovy from a higher dose of Mounjaro, it’s unlikely that you’ll need to start from the lowest dose. Your starting dose of Wegovy will depend on what dose of Mounjaro you were on, and what your prescriber thinks is safe and suitable for you. 

Will I gain weight while switching from Mounjaro to Wegovy?

It’s unlikely you’ll gain weight when switching, as the effects of Mounjaro will continue during the seven days after your final dose. You will then immediately start taking Wegovy, which will continue to work in the same way. This means you can continue losing weight while switching, especially if you’re sticking to your diet and exercise plan.

Do I need to change my diet after switching?

No, most people won’t need to make any changes, especially if they’re already following a healthy diet. As with Mounjaro, it’s best to stick to a well-balanced diet and limit high-fat foods, alcohol, and caffeine, as these can trigger or worsen symptoms like nausea and indigestion. If you’re already eating well on Mounjaro, there should be nothing to worry about.

Why should I switch to Wegovy from Mounjaro?

There are many reasons you might want to switch from Mounjaro to Wegovy, whether it’s due to cost or how the treatment is working for you. What matters most is finding a treatment that supports your weight loss journey. The decision is yours to make with your prescribing pharmacist, and there’s no “right” or “wrong” choice, only what works best for you. We’ll make sure you’re on the right treatment for your needs, so you can lose weight safely and sustainably to achieve and maintain a healthy BMI.

Get healthcare support when you need it

Whatever weight loss medication you would prefer, our dedicated team is here to support you every step of the way. If you need guidance, call us on 01695 474 433 or submit your request directly here.

"We're committed to making your healthcare journey as simple, safe and convenient as possible," explains Jason. "When you order from us, you'll benefit from expert clinical support, convenient reorder reminders, and carefully curated resources to help you maintain momentum toward your weight loss goals."