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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Mounjaro vs Wegovy: UK Price Comparison
Both Mounjaro and Wegovy are prescription-only weight loss injections available in the UK, but they differ significantly in price, mechanism, and dosing schedules. Understanding these differences helps you and your prescriber decide which medication might be most suitable. This guide compares both options factually, covering costs, doses, clinical trial results, and eligibility. Both require a clinical assessment before prescription, whether through NHS specialist services or private online prescribing.
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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/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — 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 — 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.
How Mounjaro and Wegovy Compare: Mechanism, Doses, and Costs
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates two natural hormone pathways, which is why it differs mechanically from Wegovy. In the SURMOUNT-1 clinical trial, participants taking the maximum 15 mg dose lost an average of approximately 20.9% of their body weight over 72 weeks.
Wegovy (semaglutide) is a single GLP-1 receptor agonist. In the STEP-1 trial, the maximum 2.4 mg dose resulted in an average weight loss of approximately 14.9% over 68 weeks. Both medications are used alongside a reduced-calorie diet and increased physical activity — medication alone is not sufficient for weight loss results.
UK private pricing ranges from approximately £129–£320 per month depending on dose and provider. NHS access is through specialist weight management services where available, though waiting lists vary significantly by region. Individual results vary considerably — trial data represents averages, not assured outcomes for any individual.
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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 — all stored privately in your browser.
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Key Differences: Dosing, Mechanism, and What This Means for You
Mounjaro dosing starts at 2.5 mg weekly, escalating by 2.5 mg every 4 weeks to a maximum of 15 mg. Wegovy starts at 0.25 mg, escalating more gradually to 2.4 mg. The approximate equivalent dose for Mounjaro 10 mg is Wegovy 1.7 mg, and Mounjaro 15 mg roughly corresponds to Wegovy 2.4 mg — though any medication switch must be managed by your prescriber.
Neither medication is more effective for everyone. Some people respond better to the dual mechanism of Mounjaro, whilst others see good results with Wegovy's single mechanism. A licensed prescriber assesses your individual health profile, medical history, and preferences to recommend the most suitable option. Both require consistent use alongside lifestyle changes to achieve results. Cost, availability, and side effect tolerance are also personal factors in choosing between them.
- 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 → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 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 | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/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 — 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 Mounjaro cost in the UK compared to Wegovy?
Private UK pricing typically ranges from £129–£320 per month for both medications, depending on the dose and provider. Mounjaro's higher doses (up to 15 mg) may sometimes cost more than Wegovy's maximum dose (2.4 mg), but pricing varies by pharmacy. NHS access is free but availability is limited to specialist services with potential waiting lists.
What is the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist, whilst Wegovy is a GLP-1-only agonist. Mounjaro starts at 2.5 mg weekly (up to 15 mg), Wegovy starts at 0.25 mg weekly (up to 2.4 mg). SURMOUNT trial data showed Mounjaro at 15 mg achieved approximately 20.9% average weight loss; STEP trials showed Wegovy at 2.4 mg achieved approximately 14.9% average weight loss.
Which weight loss injection is better — Mounjaro or Wegovy?
Neither is universally "better" — suitability depends on individual health factors, side effect tolerance, cost, and availability. A prescriber assesses your personal circumstances, medical history, and preferences to recommend the most appropriate medication. Both require clinical assessment and work best alongside dietary changes and physical activity.
Can I switch from Wegovy to Mounjaro?
Yes, switching is possible, but must be managed by your prescriber. Approximate dose equivalences exist (Wegovy 1.7 mg ≈ Mounjaro 10 mg, Wegovy 2.4 mg ≈ Mounjaro 15 mg), but there is no official conversion chart. Your prescriber will advise on timing and any adjustment period needed during a switch.
Is Mounjaro available on the NHS in the UK?
Yes, tirzepatide (Mounjaro) is approved by NICE for NHS use within specialist tier 3 weight management services. However, availability varies significantly by region and local commissioning decisions. NHS access typically involves referral from your GP and may include substantial waiting lists. Private prescription is available without NHS referral.
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