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
Free tracker included with every download this week
Why Is Wegovy Cheaper Than Mounjaro in the UK?
Wegovy and Mounjaro are both prescription-only weight management injections available in the UK, but Wegovy typically costs less. The price difference comes down to manufacturing costs, market competition, mechanism of action, and how long each medication has been available. Both work through GLP-1 pathways but use different approaches, which affects how they're priced by manufacturers and dispensed through UK pharmacies. Understanding the cost difference can help you and your GP make an informed choice about which medication might be right for you.
10,000+ calculations today · NHS-aligned thresholds · 100% free
Calculate Your BMI Instantly
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 Mechanism Differences Affect Pricing
Wegovy (semaglutide) and Mounjaro (tirzepatide) work through different mechanisms, and this influences their development and manufacturing costs. Wegovy is a GLP-1 receptor agonist only — it activates a single hormone pathway to regulate appetite and blood sugar. Mounjaro is a dual GIP and GLP-1 receptor agonist — it activates two hormone pathways simultaneously, which requires more complex chemical engineering.
The SURMOUNT clinical trials showed Mounjaro helped participants lose approximately 15–21% of body weight, whilst the STEP trials showed Wegovy achieved around 14.9% average weight loss. Mounjaro's dual mechanism and newer technology typically costs more to develop and manufacture. Additionally, Novo Nordisk (Wegovy's manufacturer) has had semaglutide on the market longer, allowing for established production efficiency and competitive pricing. Eli Lilly's tirzepatide (Mounjaro KwikPen) is newer, which can mean higher initial pricing as the company recovers research and development investment.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Individual Suitability and Prescriber Assessment
Cost alone should not determine which medication is right for you. Both Wegovy and Mounjaro require a clinical assessment from a UK-licensed prescriber before prescription, and eligibility depends on your BMI and health profile. Use our free GLP-1 weight loss calculator to estimate potential results with either medication, and our free BMI calculator to check your starting point.
Your prescriber will assess whether tirzepatide or semaglutide is more appropriate based on your individual circumstances, medical history, and response to treatment. Some people respond better to Mounjaro's dual mechanism, whilst others achieve excellent results with Wegovy. NHS guidance on Mounjaro from NICE supports its use within specialist services, and both medications are now available through private UK prescribers following clinical assessment. The cheaper option isn't always the best option for your personal health outcomes.
- 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 Mounjaro more expensive because it works better?
Mounjaro's higher cost reflects its newer dual-mechanism technology and manufacturing complexity, not necessarily superior results. Clinical trials show both achieve significant weight loss — Mounjaro approximately 15–21% and Wegovy approximately 14.9%. Individual outcomes vary. Your prescriber will assess which suits your health profile best.
Why is Wegovy cheaper if both are prescription-only injections?
Novo Nordisk established semaglutide production years ago, allowing competitive UK pricing. Eli Lilly's Mounjaro KwikPen is newer, so initial pricing is higher to recover development costs. As Mounjaro becomes more established, UK pricing may become more competitive over time.
Will the NHS prescribe Wegovy instead of Mounjaro because it costs less?
NHS prescribing decisions through specialist services are based on clinical appropriateness and NICE guidance, not cost alone, though budget considerations do affect tier 3 services. Private prescribers may consider cost as one factor alongside clinical suitability. Your GP can discuss which option is available through your local NHS service.
Does a lower price mean Wegovy is less effective?
No. Price reflects manufacturing and market factors, not efficacy. Both medications are clinically effective for weight management. Wegovy clinical trials demonstrated meaningful weight loss averaging nearly 15% of body weight when combined with dietary and lifestyle changes.
How much cheaper is Wegovy compared to Mounjaro in the UK?
Pricing varies by dose and provider. Wegovy typically costs £129–£199 monthly depending on dose, whilst Mounjaro ranges from £149–£299 monthly. Prices vary between private prescribers. NHS access costs nothing to patients but availability depends on your local specialist service.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.