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 Injection Price Increase vs Wegovy
Mounjaro injection costs in the UK have increased in recent years, leading many people to compare it with Wegovy as an alternative weight loss injection. Both are prescription-only medications licensed for adults with obesity or overweight with health conditions, but they differ in mechanism, dosing, and cost. This guide explains the price context, how Mounjaro and Wegovy compare clinically, and how to access both through NHS specialist services or private prescribing in the UK.
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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 Clinically
Mounjaro (tirzepatide) and Wegovy (semaglutide) are both once-weekly weight loss injections licensed in the UK, but they work differently. Mounjaro is a dual GIP and GLP-1 receptor agonist, activating two hormone pathways to regulate appetite and blood sugar. Wegovy is a GLP-1 receptor agonist only, activating a single pathway. In clinical trials, Mounjaro showed an average weight loss of around 15–21% of body weight across different doses, whilst Wegovy demonstrated approximately 14.9% average weight loss. These are trial averages with individual results varying significantly. Mounjaro's maximum dose is 15 mg weekly, whilst Wegovy's is 2.4 mg weekly. Both require a prescription, clinical assessment, and are used alongside reduced-calorie diet and increased physical activity. Try our free GLP-1 weight loss calculator to estimate potential outcomes at different doses.
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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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UK Pricing and Access for Both Medications
Mounjaro and Wegovy costs vary significantly depending on whether you access them through NHS specialist weight management services or private prescribing. NHS access is through tier 3/4 specialist services (referral required from your GP), with availability and waiting times varying by region. Private costs typically range from £129–£320 monthly depending on dose and provider. Both medications are prescription-only; neither is available without a clinical assessment from a licensed UK prescriber. Costs may increase due to supply, manufacturing, and demand factors. Your prescriber can discuss which medication suits your individual health, preferences, and budget. Use our free BMI calculator to check your baseline before speaking with your GP about eligibility for specialist weight management services.
- 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.
Why has Mounjaro injection price increased in the UK?
Mounjaro prices have risen due to increased demand, supply chain factors, and manufacturing costs. As a newer dual GIP/GLP-1 medication with stronger clinical trial results compared to earlier GLP-1 injections, demand has exceeded initial supply. Prices also reflect NHS reimbursement rates and private market competition.
Is Mounjaro or Wegovy cheaper in the UK?
Costs vary by provider and dose. Generally, both medications cost roughly £129–£320 monthly privately. NHS costs (if eligible) depend on your regional commissioning. Your prescriber can advise on cost-effectiveness for your individual situation and may discuss both options.
Can I get Mounjaro on the NHS in the UK?
Yes. NICE has approved tirzepatide (Mounjaro) for NHS use within specialist tier 3/4 weight management services. Access requires a GP referral and meets strict BMI and health criteria. Availability and waiting times vary significantly by region and local commissioning.
What's the main difference between Mounjaro and Wegovy mechanisms?
Mounjaro activates two hormone pathways (GIP and GLP-1), whilst Wegovy activates GLP-1 only. This dual mechanism may explain Mounjaro's slightly higher average weight loss in trials. However, individual response varies, and which is more suitable depends on your personal health factors assessed by your prescriber.
How do I know which weekly weight loss injection is right for me?
A licensed prescriber will assess your medical history, current medications, health conditions, BMI, and preferences. Both Mounjaro and Wegovy require prescription and clinical assessment. Neither is suitable for everyone, and your prescriber will discuss risks, benefits, costs, and dose titration schedules tailored to you.
Ready to take control of your weight loss journey?
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