How to Switch Between Mounjaro & Wegovy in the UK: The Complete Guide (2026)

Switching between Mounjaro and Wegovy is more common than you might think. And it’s completely doable.

What it isn’t, is a simple swap. These are two different medications with different mechanisms, different dose ranges, and different effects on your body. 

We’ve covered everything for you - what’s involved, what to expect, and how to do it safely. Each section links to a dedicated article that goes deeper on that specific topic.

Mounjaro vs Wegovy: Understanding the Difference Before You Switch

This is the fundamental 

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The biggest difference between the two medications is GIP, a second gut hormone that Mounjaro works on and Wegovy doesn’t. If you’re switching from Wegovy to Mounjaro, GIP agonism will be new to your body and hence the adjustment period can take some time to adjust to it.

Here’s a detailed guide on everything you need to know when switching from Wegovy to Mounjaro.

The Most Common Reasons Women Switch GLP-1 Medication

• Supply disruption: Mounjaro faced availability issues in 2025, particularly at higher doses. Some women switched and settled with Wegovy.
• Cost: Mounjaro’s price for higher doses increased significantly from September 2025. Wegovy, especially with the 7.2mg dose approved in January 2026, offered a great alternative with comparable results.
• Plateau: Weight loss stalls for some women, and switching can help resume it.  
• Side effects: For some women, Mounjaro’s dual action can be a bit too much to handle, making them try Wegovy. 
• Cardiovascular benefits: Wegovy has now received a cardiovascular benefit licence (NICE, April 2026). So, clinicians may advise women with relevant cardiac history to switch.
• Provider change: A new provider may prescribe differently based on their clinical pathway.

Is It Safe to Switch Between Mounjaro and Wegovy?

Yes, but only with the right support. The MHRA has confirmed that switching between GLP-1 medicines should only be done under professional guidance as they differ in strength, mechanism, and titration. You must disclose all information about your weight loss journey, treatment history, any other medication, etc. to your clinician.

Once your clinician approves the switch, and helps you plan your dosage, you can start the other medication one week after you stop the previous one.

Mounjaro to Wegovy Dose Conversion: Understanding the Difference

Can You Directly Convert Your Mounjaro Dose to a Wegovy Dose?

No. There is no officially published dose conversion chart between Mounjaro and Wegovy. This is because the medications are different molecules measured in different units, working through different hormonal pathways. The number on the pen does not correspond to a one-is-to-one comparison in strength.

This is where the professional guidance comes in. Your prescriber / clinician reviews your treatment history, your tolerance, your blood test results, and how long you’ve been at your current dose to decide the starting point for your new medication. 

There is no formula. It’s what’s right for you. But based on our experience and clinical data, here’s what generally happens - 

• Mounjaro to Wegovy: most prescribers start Wegovy at 0.25mg–1mg depending on your history, even if you were on Mounjaro 15mg
• Wegovy to Mounjaro: You’ll start at 2.5mg or 5mg regardless of your previous Wegovy dose, because your body will need time to adjust to GIP, and a lower dose helps ease the adjustment period.

This is how your prescriber protects you from unnecessary side effects during the transition.

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For the dose-by-dose breakdown and a week-by-week timeline of what to expect, read: Switching from Mounjaro to Wegovy: Dosage and What to Expect.

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How the Switching Process Works

Step 1: Contact Your Current Provider

Let your clinician know that you’re considering a switch and why. Don’t stop your current medication. Let your clinician develop a tailored plan for you. An unmanaged gap in treatment can cause rapid appetite return and unnecessary side effects when you restart.

Step 2: Choose a New Provider (or Stay With Your Current One)

If your current provider offers both medications, the switch can happen within the same programme. If you’re moving to a new provider, you don’t need permission or a referral from your previous one. Just be ready with the information as below to give your new provider - 

• Your current medication and dose
• Date of your last injection
• How long you’ve been at your current dose
• Any side effects you’ve experienced
• Your most recent weight and blood test results if available
• Any other medications you take

This helps them understand the entire picture and plan the switch properly for you.

Not sure what to look for in a provider? Read: How to Choose or Switch Mounjaro Providers in the UK.

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What Happens to Your Prescription

A Mounjaro prescription cannot be used to obtain Wegovy, or vice versa. Your new provider will issue an independent prescription after your clinical assessment.

Switching from Mounjaro to Wegovy

This is the most common switch we’ve seen in 2026, especially after the cost changes and the new Wegovy 7.2mg approval. Here are the key things you need to know:

• One-week gap between your last Mounjaro injection and first Wegovy dose will be needed
• You’ll start Wegovy at a lower dose than your current Mounjaro dose
• Appetite suppression may feel different initially as the GIP effect fades away from your body. It’s normal and temporary. 
• Your weight loss journey will continue smoothly as long as the switch is managed well

For the full step-by-step guide including what your clinician looks for and how to prepare, read: How to Switch from Mounjaro to Wegovy Safely. 

Switching from Wegovy to Mounjaro

This switch we’ve mostly seen when women see their weight loss journey plateau with Wegovy and are wanting to try Mounjaro for its dual-action (GLP-1 + GIP) mechanism. If you’re one of them, here’s what you need to know - 

• You’ll need a one-week gap between your last Wegovy injection and first Mounjaro dose
• Semaglutide’s half-life is approximately 7 days, which means it’ll be at 50% efficacy in 7 days and hence safe for you to take another medication
• You’ll start Mounjaro at 2.5mg or 5mg regardless of your Wegovy dose
• Your body may take its time to adjust to the new GIP mechanism.
• Side effects are almost common between both medications. But Mounjaro, being stronger, can be a bit more intense for some women. Starting lower helps here.

Again, for the full guide including dosage table and patient experiences: Switching from Wegovy to Mounjaro →

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What to Expect in the Weeks After Switching

Will You Experience Side Effects After Switching?

Yes, some adjustment is normal. Your body is responding to a different molecule, a different dose, and a different hormonal signal. Nausea, fatigue, and mild GI changes are common in the first 2–4 weeks at each new dose level. They tend to settle after that.

Will You Keep Your Weight Loss Progress?

Yes, if the switch is managed well. The medication changing doesn’t erase the progress you’ve made. There will be a short adjustment period where progress may slow temporarily, but momentum typically resumes as you titrate up to your new maintenance dose.

Switching Between Mounjaro and Wegovy at SheMed

At SheMed, every switch, whether you’re coming from another provider or changing medication within our programme, starts with an at-home blood test. This gives our clinical team a full metabolic picture before anything is prescribed: thyroid function, liver enzymes, HbA1c, and cholesterol.

For us, it’s about your overall health, including mental, and not just the number on the scale.

Private pricing is indicative based on market data from April 2026. Costs vary by provider and may or may not include consultation fees, needles, and delivery. Always ask for the all-in total cost before committing.

Cost Benefit Analysis: Mounjaro vs Wegovy

Mounjaro starter doses are for around £133–£190, similar to the Wegovy starter doses which are for around £130–£150. The difference comes in when the dosage increases.

For a woman on Mounjaro 12.5mg or 15mg, the monthly private cost post-September 2025 is now £330–£375. Wegovy, on the other hand would cost around £200–£295/month for an equivalent dose. This means a saving of up to £960/year. Even if you take Wegovy 7.2mg, that’s around £295+/month, still below the Mounjaro top-dose price.

So, if cost is the driver for you, you have a clear answer there.

NHS Access: What You Can Get and How

Both medications are available on the NHS, but access remains limited. Here’s the current picture:

There’s a waiting list of 6-17 months in most areas for both. The NHS GP prescribing for Mounjaro is expected to roll our through Integrated Care Boards (ICBs) from 2026–27 with thresholds widening gradually.

Around 1.2 million people in England are eligible for Wegovy for cardiovascular indications that include BMI 27+ with a history of heart attack, stroke, or peripheral arterial disease. NHS trusts must make it available within 90 days of final NICE guidance (expected from late summer 2026). This is the fastest-opening NHS access route currently available.

Switching at SheMed: Injections and the Wegovy Pill

At SheMed, every switch starts with a full at-home blood test. This gives our clinical team a complete metabolic picture before anything is prescribed, covering thyroid function, liver enzymes, HbA1c, and cholesterol. Your starting dose is then decided by a clinician, not an algorithm.

We offer Mounjaro and Wegovy as weekly injections, as well as the Wegovy pill, oral semaglutide in a once-daily tablet, for women who prefer not to inject. The pill contains the same active ingredient as the Wegovy pen and is available in four doses: 1.5mg, 4mg, 9mg, and 25mg. It is a practical option for women who travel frequently, have no fridge access, or find needles a barrier to starting or continuing treatment.

If you are switching from Mounjaro and want to move to semaglutide, your clinician will assess whether the injection or the pill is the more suitable format for you based on your health profile and lifestyle.

We are a community of 100,000+ women. First month from £59 for injections, or from £69 for the Wegovy pill, subject to clinical approval.

See the switch and save offer | Learn more about the Wegovy pill

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Frequently Asked Questions

Can you switch from Mounjaro to Wegovy?

Yes. It’s safe and increasingly common in the UK. The switch should always be done under medical supervision. You’ll need a new prescription, a one-week washout period, and a clinician-decided starting dose, which will be lower than your current Mounjaro dose.

Can you switch from Wegovy to Mounjaro?

Yes. You’ll start at 2.5mg or 5mg regardless of your current Wegovy dose, because Mounjaro’s GIP pathway is entirely new to your body. 

How long do you have to wait between switching?

One week is the standard washout period. Mounjaro (tirzepatide) has a half-life of approximately 5 days and Wegovy (semaglutide) has a half-life of approximately 7 days. The one week gap allows the previous medication to get cleared from your system sufficiently.

Will I lose my weight loss progress when I switch?

Not if the switch is properly managed. There may be a short adjustment period where progress slows, but your body remains at its current weight and metabolic baseline. Your journey will resume once your body accepts the new mechanism.

Do I need to start from the lowest dose when switching?

Usually yes, or close to it. There is no official dose conversion between the two medications. Your prescriber will decide a starting dose based on your history and tolerance, but the starting point will typically be lower than where you left off with the previous medication.

Can I change providers when I switch medication?

Yes. You don’t need permission from your current provider to move to a new one. All you need is your treatment history including current dose, date of last injection, and any side effects to help your new prescriber make the right clinical decision.

What information do I need to give a new provider when switching?

You do not need a referral or permission from your current provider, but you should come prepared with the following:

• Your current medication name and dose
• The date of your last injection
• How long you have been at your current dose
• Any side effects you have experienced
• Your most recent weight
• Any blood test results if available
• Any other medications you take

The more complete your treatment history, the better the clinical decision your new provider can make on your starting dose.

How long does it take for Wegovy to work after switching from Mounjaro?

Allow eight to twelve weeks before making any judgement about whether Wegovy is working after a switch. Here is what that timeline looks like:

• Week 1: Your body begins adjusting to a different hormonal signal. Appetite suppression may feel less defined than on Mounjaro. Some mild nausea is common.
• Weeks 2 to 4: The adjustment period ends. Appetite suppression becomes more consistent and predictable.
• Weeks 4 to 8: Wegovy's effects become clearer. Cravings quieten and weight loss typically resumes momentum.
• Months 2 to 4: Titration continues and most people experience their most noticeable progress during this phase.
• Month 4 onwards: At or near your maintenance dose, you are approaching full efficacy.

Mounjaro activates both GLP-1 and GIP pathways, while Wegovy activates GLP-1 only. The appetite suppression will feel different in the early weeks. This is normal, expected, and temporary.

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Sources & Further Reading

1. MHRA — GLP-1 Medicines for Weight Loss and Diabetes (GOV.UK, updated 2026)

2. SURMOUNT-1 Trial — Tirzepatide Once Weekly for the Treatment of Obesity (NEJM, 2022)

3. SURMOUNT-5 Trial — Tirzepatide vs Semaglutide (NEJM, July 2025)

4. STEP UP Trial — Semaglutide 7.2mg (Lancet Diabetes Endocrinol, 2025)

5. NICE — Semaglutide for Cardiovascular Risk Reduction (April 2026)

6. NICE TA1026 — Tirzepatide (Mounjaro) for Managing Overweight and Obesity

7. NHS — Obesity Treatment Overview

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