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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5mg Mounjaro Wegovy Equivalent — UK Comparison
If you're comparing weight loss injections in the UK, you may have heard that 5mg Mounjaro is roughly equivalent to 0.5mg Wegovy. However, these two prescription-only medications work differently — Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1 agonist only. This guide explains the approximate equivalence, how NHS prescribing works for both, and what this means for your weight loss journey. Both require a clinical assessment before prescription, whether through NHS specialist services or private prescribers.
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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.
Mounjaro vs Wegovy Dose Equivalence in UK Context
Approximate dose equivalence between Mounjaro and Wegovy helps when comparing these weight loss injections, though there is no official NHS conversion chart. Based on clinical practice guidelines and clinical trial data, 5mg Mounjaro is roughly equivalent to 0.5mg Wegovy in terms of efficacy range, though individual response varies significantly.
- 5mg Mounjaro: typical first maintenance dose after titration; approximately 15% average body weight loss in clinical trials
- 0.5mg Wegovy: second escalation dose in the titration schedule; approximately 10–12% average body weight loss
- Important: these are approximate comparisons only — any switch between medications must be managed by your prescriber, not self-directed
- Tirzepatide (Mounjaro) and semaglutide (Wegovy) act through different mechanisms, so direct equivalence does not account for individual variation
Use our GLP-1 weight loss calculator to see projected weight loss at different doses of either medication — results vary based on your starting weight and adherence to dietary changes.
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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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NHS Eligibility and Prescribing Routes in the UK
Both Mounjaro and Wegovy are prescription-only medicines in the UK and require clinical assessment before prescription. The NHS does fund both medications through NICE-approved tier 3 weight management services, but access varies significantly by region and waiting lists can be lengthy. You'll typically be referred to a specialist weight management service by your GP if you meet eligibility criteria (BMI ≥30, or BMI 27–29.9 with weight-related health conditions like type 2 diabetes or hypertension).
Alternatively, both medications are available privately through GPhC-registered online prescribers following an online clinical assessment — this route typically has faster access. Whether you choose NHS or private prescribing, your healthcare provider will assess which medication is most appropriate for you based on your individual health profile, not based on dose equivalence charts alone.
- 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.
Is 5mg Mounjaro definitely the same as 0.5mg Wegovy?
No — these are approximate equivalences based on clinical practice, not official conversions. Mounjaro (tirzepatide) is a dual mechanism GIP+GLP-1 agonist, while Wegovy (semaglutide) is GLP-1 only. Individual response varies significantly. Any medication switch must be managed by your prescriber.
Can I switch from Mounjaro 5mg to Wegovy without seeing my GP?
No. Any switch between weight loss medications must be managed by your prescriber — whether through NHS or private services. Do not attempt to switch doses yourself. Your GP or prescriber will advise on timing and any dose adjustments needed.
How do I check my eligibility for Mounjaro or Wegovy on the NHS?
Speak to your GP about referral to your local tier 3 weight management service. You typically need a BMI ≥30 or BMI 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea, cardiovascular disease). Eligibility and waiting times vary by region.
What's the difference between Mounjaro and Wegovy in terms of weight loss results?
Clinical trials show Mounjaro 15mg achieves approximately 20.9% average body weight loss, while Wegovy 2.4mg achieves approximately 14.9% average body weight loss. However, individual results vary widely — factors like diet, exercise, starting weight, and adherence all affect outcomes.
Can I access both Mounjaro and Wegovy privately in the UK without NHS referral?
Yes — both are available through private online prescribers following a clinical assessment. This route does not require NHS referral but involves direct cost (typically £150–£300 per month depending on dose). Always use a GPhC-registered pharmacy to ensure safe, regulated prescribing.
Ready to take control of your weight loss journey?
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