The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Switching From Mounjaro To Wegovy In The UK
If you're currently on Mounjaro (tirzepatide) and considering switching to Wegovy (semaglutide), you'll need to understand the UK cost differences, how the transition works, and what access routes are available to you. Both are prescription-only GLP-1 medications, but they differ in mechanism, dosing, and availability through the NHS versus private prescription. This guide covers everything you need to know about making the switch, including cost comparisons and how to access either medication in the UK.
10,000+ calculations today ยท NHS-aligned thresholds ยท 100% free
Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/mยฒ).
While BMI isn't a perfect measure โ it doesn't account for muscle mass, bone density, or fat distribution โ it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage โ a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Wegovy Cost In The UK โ Private Prescription Pricing
Wegovy is available in the UK through private prescription following an online clinical assessment with a UK-licensed prescriber. Private Wegovy costs typically range from ยฃ129 to ยฃ320 per month, depending on the dose you're prescribed and the provider you use. The starting dose (0.25 mg) is usually at the lower end of this range, while maintenance doses (1.7 mg or 2.4 mg) cost more. Unlike Mounjaro, which uses KwikPen devices containing four doses per month, Wegovy comes as individual pre-filled injection pens. Costs are generally similar to Mounjaro in the private market, though some providers offer different pricing structures. It's worth comparing costs across GPhC-registered online pharmacies before committing to a provider โ prices vary and some offer loyalty discounts or bulk purchasing options. The cost remains consistent whether you're switching from another medication or starting new treatment.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care โ from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated โ all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress โ completely free.
NHS Access And The Switch From Mounjaro To Wegovy
On the NHS, access to both Mounjaro and Wegovy is through specialist tier 3 or tier 4 weight management services. You cannot simply switch from one to the other at your GP surgery โ each change must be managed by the specialist service you're under. Waiting lists for NHS specialist weight management services are long in most areas (often 6โ12 months or longer), which is why many people on Mounjaro already access it privately. If you're on NHS Mounjaro and want to switch to Wegovy, you'd need to discuss this with your NHS specialist team. If you're on private Mounjaro and considering switching to private Wegovy, you can access a new private prescription through an online consultation without needing NHS involvement. Both options require clinical assessment to confirm you meet eligibility criteria and that the new medication is appropriate for you.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg โ 5mg โ 7.5mg โ 10mg โ 12.5mg โ 15mg
- GLP-1 receptor agonist
- Up to 15โ17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg โ 0.5mg โ 1mg โ 1.7mg โ 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15โ22.5% | 12โ17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20โ32 weeks | 16โ20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | ยฃ150โยฃ250/month | ยฃ150โยฃ300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users โ supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
How much does Wegovy cost on private prescription in the UK?
Private Wegovy typically costs ยฃ129โยฃ320 per month depending on dose. Starting doses (0.25 mg) are usually cheaper, while maintenance doses (2.4 mg) are more expensive. Costs vary between providers โ compare GPhC-registered pharmacies for the best price. Most are similar to Mounjaro pricing in the private market.
Can I switch from Mounjaro to Wegovy on the NHS?
If you're on NHS Mounjaro through a specialist weight management service, any medication change must be managed by that service. You'd need to discuss switching with your NHS team โ you cannot simply request Wegovy. Waiting lists for specialist services are long in most areas.
Do I need a new prescription to switch to Wegovy?
Yes. Whether you're switching on the NHS or privately, your previous Mounjaro prescription ends and you need a new prescription for Wegovy. Your prescriber will assess whether Wegovy is appropriate for you before issuing a new prescription. This requires a clinical consultation.
What's the difference between Mounjaro and Wegovy in terms of cost and availability?
Both cost similarly on private prescription (ยฃ129โยฃ320/month). The main difference is mechanism: Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro uses KwikPens with four doses; Wegovy comes as individual pens. Both require prescription and clinical assessment.
What should I do if I want to switch from private Mounjaro to private Wegovy?
Contact a UK-licensed online prescriber or GPhC-registered pharmacy offering Wegovy. Complete an online health assessment. If approved, a new prescription will be issued for Wegovy at an appropriate starting dose. Costs and providers vary โ compare options before committing.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.