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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 7.5mg vs Wegovy — UK Cost and Comparison Guide
If you're searching for the cheapest 7.5mg Mounjaro in the UK, you're likely weighing it against Wegovy as an alternative weight loss injection. Both are prescription-only GLP-1 medications available through UK prescribers, but they work differently, cost differently, and suit different individuals. This guide compares both medications factually—including clinical trial data, mechanisms, costs, and how prescribers decide which is right for you—so you can understand your options before speaking to your GP or a licensed prescriber.
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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 7.5mg and Wegovy Work Differently
Mounjaro (tirzepatide) at 7.5mg is a dual GIP and GLP-1 receptor agonist. This dual mechanism activates two natural hormone pathways—GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1)—which may help regulate appetite more strongly than GLP-1 alone. Mounjaro is dosed weekly in increments of 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg maximum.
Wegovy (semaglutide) is a single GLP-1 receptor agonist only. It activates the GLP-1 pathway, which signals fullness and reduces appetite. Wegovy escalates from 0.25mg to a maximum of 2.4mg once weekly. In STEP clinical trials, Wegovy showed an average weight loss of approximately 14.9% body weight. Mounjaro's SURMOUNT trials showed approximately 15–21% average body weight loss depending on dose, with the 7.5mg dose showing around 18–19% loss on average.
- Mounjaro mechanism: dual GIP + GLP-1 activation
- Wegovy mechanism: GLP-1 activation only
- Both are once-weekly weight loss injection UK medications
- Individual results vary significantly
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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 Costs, Availability, and How Your Prescriber Decides
Mounjaro 7.5mg costs typically range from £150–£220 per month depending on the UK prescriber and private pharmacy. Wegovy costs are similar, typically £130–£200 per month. NHS access to both is through specialist tier 3 weight management services—waiting lists vary by region and can be substantial. Private prescribing via a UK-licensed prescriber and GPhC-registered pharmacy is faster but not subsidised.
Your prescriber will assess which medication suits you based on your BMI, medical history, and individual health needs. Both require a clinical assessment before prescription. Neither is assured to produce specific weight loss results—both work alongside reduced-calorie diet and increased physical activity. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses. Your GP or prescriber will recommend the medication most appropriate for your circumstances after reviewing your full health profile.
- 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 does Mounjaro at 7.5mg cost more than Wegovy in the UK?
Mounjaro's dual mechanism (GIP + GLP-1) and newer formulation mean manufacturing costs are higher. Both are subject to similar NHS/private pathways, but Mounjaro's emerging status and dual action typically command a slight price premium. Costs vary by private prescriber and pharmacy.
Which is more effective—Mounjaro 7.5mg or Wegovy?
Clinical trials (SURMOUNT vs STEP) suggest Mounjaro may produce slightly higher average weight loss, but individual results vary considerably. Effectiveness depends on your body chemistry, adherence, diet, and activity. Your prescriber will recommend the most suitable option based on your health profile and medical history.
Can I switch from Wegovy to Mounjaro 7.5mg?
Yes, switching between medications is possible but must be managed by your prescriber. There is no official conversion chart—the approximate equivalent of Wegovy 1.7mg is roughly Mounjaro 10mg. Any switch requires clinical reassessment and should not be done without prescriber guidance.
Do I need a prescription for either Mounjaro 7.5mg or Wegovy in the UK?
Yes, both are prescription-only medications in the UK. Access is through NHS specialist weight management services (tier 3) or private prescribing following an online clinical assessment with a UK-licensed prescriber. Neither is available over-the-counter.
How do I know which weight loss injection UK option is right for me?
Your GP or licensed prescriber will assess your BMI, medical history, weight-related health conditions, and individual suitability. Try our BMI calculator to check your starting point, then discuss with a healthcare professional who can review your full medical picture and recommend the most appropriate prescription weight loss treatment.
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.