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: Cost, Discounts & Eligibility in the UK
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight management injections available in the UK, but their cost and discount availability differ significantly. Understanding the pricing structure and how to access potential savings can help you make an informed decision alongside your prescriber. This guide compares both medications factually, covering clinical differences, dose titration schedules, and how UK access through NHS NICE approval or private prescribing affects overall cost.
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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.
Clinical Differences: SURMOUNT vs STEP Trial Data and Mechanisms
Mounjaro and Wegovy work through different mechanisms, which is reflected in their clinical trial outcomes. Mounjaro is a dual GIP and GLP-1 receptor agonist, activating two hormone pathways simultaneously. In the SURMOUNT-1 clinical trial, participants on the maximum 15 mg dose achieved an average weight loss of approximately 20.9% of body weight over 72 weeks. Wegovy is a GLP-1 receptor agonist only, activating a single hormone pathway. In the STEP-1 trial, participants on 2.4 mg achieved approximately 14.9% average weight loss over 68 weeks.
Individual results vary significantly. Both medications are prescribed alongside a reduced-calorie diet and increased physical activity. The dual mechanism of Mounjaro may offer different results for some individuals, while Wegovy's longer track record and single mechanism may suit others better. A prescriber assesses which is more appropriate based on your personal health profile, not cost alone.
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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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Dose Titration, Cost Implications, and UK Access Routes
Mounjaro dose titration: Starts at 2.5 mg weekly for 4 weeks, escalating by 2.5 mg increments every 4 weeks up to 15 mg maximum. Each KwikPen contains 4 weekly doses. Wegovy dose titration: Starts at 0.25 mg weekly, escalating more gradually (0.25→0.5→1→1.7→2.4 mg) over 16+ weeks.
Private prescription costs vary by provider and dose. Some private prescribing services offer tiered pricing or loyalty discounts on repeat prescriptions, though you should verify current offers directly. NHS access through NICE-approved specialist weight management services is free at point of use, but availability is regional and waiting lists can be lengthy. Your GP can refer you to your local tier 3 service, or you can seek private prescribing without NHS referral. Neither medication has manufacturer discount programmes in the UK.
- 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.
Which costs less, Mounjaro or Wegovy, in the UK?
Private prescribing costs vary by provider and dose. Mounjaro (starting 2.5 mg) and Wegovy (starting 0.25 mg) have different pricing structures. Some providers offer discounts on repeat prescriptions. NHS access through specialist services is free. Always compare current prices directly with registered pharmacies, as costs change regularly.
Are there official discounts or vouchers for Mounjaro in the UK?
Mounjaro does not have an official manufacturer discount scheme in the UK. Some private prescribing services offer loyalty discounts on repeat prescriptions or bundle pricing. Always verify current offers with your prescriber or pharmacy directly before purchasing.
Which weight loss injection is more suitable for me — Mounjaro or Wegovy?
Suitability depends on your health profile, not cost. Your prescriber assesses eligibility, comorbidities, and medical history to recommend the most appropriate medication. Both require clinical assessment. Use our free GLP-1 weight loss calculator to explore projected outcomes, but a prescriber must make the final recommendation.
Can I get Mounjaro or Wegovy free on the NHS?
Yes, if referred to an NHS specialist weight management service. NICE has approved both tirzepatide (Mounjaro) and semaglutide (Wegovy) for NHS use. Referral is through your GP to a tier 3 service. Availability and waiting times vary significantly by region. Private prescribing does not require NHS referral but involves a cost.
How do I compare the actual cost of treatment over time?
Calculate the total cost by multiplying the cost per dose by the number of doses needed to reach maintenance dosing, then the ongoing monthly cost. For example, Mounjaro requires 4–5 months of titration; Wegovy requires approximately 4 months. Our GLP-1 weight loss calculator can help you project treatment timelines, but ask your prescriber or pharmacy for a full cost breakdown.
Ready to take control of your weight loss journey?
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