The UK's most complete GLP-1 guide
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- 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 Zepbound — UK Access and Cost Guide
Mounjaro (tirzepatide) and Zepbound are both prescription-only weight management injections available in the UK, but understanding the differences in cost, access, and how they work is essential before deciding which might suit you. This guide explains how to access each medication, what you'll pay, and how they compare for UK adults seeking weight loss support.
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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.
UK Cost and Access Differences Between Mounjaro and Zepbound
Mounjaro (tirzepatide) is manufactured by Eli Lilly and is a dual GIP and GLP-1 receptor agonist — this dual mechanism sets it apart from single GLP-1 medications. In clinical trials, Mounjaro achieved average weight loss of approximately 15–21% of body weight over 72 weeks, depending on dose. Zepbound is Novo Nordisk's brand name for tirzepatide in some markets, but in the UK, Novo Nordisk's licensed weight management injection is Wegovy (semaglutide), a GLP-1-only agonist with average weight loss around 15% body weight.
Regarding cost: Private prescription costs for tirzepatide-based injections typically range from £129–£320 per month depending on dose and provider. Wegovy private costs are similar. Both require prescription-only status and clinical assessment before dispensing. Use our free GLP-1 weight loss calculator to project potential outcomes at different doses for either medication.
Both are available through NHS specialist weight management services in some regions, though NHS access is limited and waiting times vary significantly across different ICBs (Integrated Care Boards).
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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 Route vs Private Route — How to Access in the UK
NHS route: Both tirzepatide and semaglutide can be prescribed through NHS tier 3 specialist weight management services, but only after referral from your GP and assessment by a specialist team. Many areas have long waiting lists (months to years), and availability depends entirely on your regional NHS commissioning decisions. There is no cost to you if prescribed via NHS.
Private route: Both medications are available through GPhC-registered online pharmacies following an online consultation with a UK-licensed prescriber. You complete a health questionnaire, a prescriber assesses suitability, and if approved, your prescription is dispensed. This typically takes 24–48 hours. Private costs start around £129–£320/month depending on starting dose. Neither medication is assured — prescriber assessment is essential.
Check your personal BMI and eligibility using our free BMI calculator before booking a private consultation. Adults with BMI 30+ (or 27+ with weight-related health conditions) may be eligible. Your prescriber will verify medical suitability — factors like medical history, other medications, and contraindications all matter. Always disclose full health information during your online assessment.
- 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 Zepbound available in the UK?
Zepbound is Novo Nordisk's brand name for tirzepatide sold in the US. In the UK, Novo Nordisk's licensed weight management injection is Wegovy (semaglutide), not Zepbound. Tirzepatide is available in the UK under the brand name Mounjaro, manufactured by Eli Lilly. Both are prescription-only medications requiring clinical assessment.
What's the main difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1-only agonist. This dual mechanism may explain Mounjaro's slightly higher average weight loss in clinical trials (15–21% vs 15%). Both are once-weekly injections and require prescription through NHS specialist services or private online prescribing.
How much do private Mounjaro prescriptions cost in the UK?
Private tirzepatide (Mounjaro) prescriptions in the UK typically cost £129–£320 per month, varying by dose and provider. Starting doses (2.5–5 mg) are usually lower cost; maximum doses (15 mg) are higher. Costs may include the prescription fee and the medication itself. Always clarify full costs before committing.
Can I get Mounjaro or Wegovy on the NHS in the UK?
Both medications can be prescribed through NHS tier 3 specialist weight management services, but only after GP referral and specialist assessment. Availability and waiting times vary dramatically by region. Many areas have waiting lists of many months. Ask your GP about local NHS weight management services in your area.
What do I need to do to get a private prescription for either medication?
Contact a GPhC-registered online prescribing service, complete a health questionnaire, and have an online consultation with a UK-licensed prescriber. If approved, your prescription is dispensed by a regulated pharmacy. The entire process typically takes 24–48 hours. Be honest about your medical history — prescribers must assess clinical suitability before dispensing.
Ready to take control of your weight loss journey?
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