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 Ozempic for Weight Loss in the UK
If you're exploring weight loss options in the UK, you may have heard about both Mounjaro and Ozempic. While they sound similar, there are important differences between them — particularly regarding their approved use, cost, and how to access them. This guide clarifies what each medication is, how they differ, and what you can realistically expect in terms of UK prescription and cost. Understanding these distinctions will help you make an informed conversation with your GP or prescriber about which option might suit your situation.
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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.
Mounjaro and Ozempic: What's the Key Difference?
Both Mounjaro (tirzepatide) and Ozempic (semaglutide) are prescription-only injectable medications, but they are licensed for different purposes in the UK. Mounjaro is a dual GIP and GLP-1 receptor agonist — meaning it activates two hormone pathways to help regulate appetite and support feeling fuller after meals. In clinical trials, this dual mechanism helped participants lose an average of 15–21% of their body weight.
Ozempic, by contrast, is a GLP-1 receptor agonist only — it activates one hormone pathway. Critically, Ozempic is licensed in the UK specifically for managing type 2 diabetes, not for weight loss. Using Ozempic for weight loss is technically off-label use. The licensed weight loss version of semaglutide is called Wegovy, which contains the same active ingredient at a higher dose (up to 2.4 mg) compared to Ozempic (up to 2 mg for diabetes).
- Mounjaro: Approved for weight management, once-weekly injection, doses from 2.5 mg to 15 mg
- Ozempic: Approved for type 2 diabetes, not licensed for weight loss in the UK
- Wegovy: The licensed weight loss version of semaglutide, once-weekly injection, doses from 0.25 mg to 2.4 mg
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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.
Free Weight Loss Tools & Guides
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Accessing Mounjaro vs Ozempic: Cost and How to Get Them
In the UK, Mounjaro is available both through NHS specialist weight management services and via private prescription through online consultations with UK-licensed prescribers. If accessed privately, Mounjaro typically costs between £129 and £320 per month depending on the dose — you'll pay for a full KwikPen (4 weeks supply) even if you're still titrating up. Ozempic is available on the NHS for type 2 diabetes management, but requesting it specifically for weight loss off-label is unlikely to be approved. If you want licensed weight loss treatment, Mounjaro or Wegovy are your primary options.
The private route involves an online consultation with a prescriber who reviews your health history, checks your BMI and eligibility, and issues a prescription if appropriate. You then receive your medication through a GPhC-registered pharmacy. NHS access requires referral to a tier 3 specialist weight management service — availability and waiting times vary significantly by region and ICB.
Use our free GLP-1 weight loss calculator to estimate potential outcomes with different doses of Mounjaro or Wegovy, and our BMI calculator to check your starting point. Both tools help you understand your eligibility and what realistic results might look like based on clinical trial data.
- 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 Ozempic the same as Mounjaro?
No. Ozempic (semaglutide) is a GLP-1 medication licensed for type 2 diabetes in the UK, not weight loss. Mounjaro (tirzepatide) is a dual GIP/GLP-1 medication licensed specifically for weight management. Wegovy is the licensed weight loss version of semaglutide. Using Ozempic for weight loss is off-label.
Can I get Mounjaro on the NHS for weight loss?
Mounjaro is available on the NHS through specialist tier 3 weight management services, but access varies significantly by region and may involve waiting lists. Private online prescription through a UK-licensed prescriber is an alternative that doesn't require an NHS referral.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129 to £320 per month depending on dose. You buy a full KwikPen (4 weeks' supply) each month. Prices vary between pharmacies, so it's worth comparing. Always check that the pharmacy is GPhC-registered.
How does Mounjaro compare to Wegovy for weight loss?
Mounjaro uses a dual mechanism (GIP + GLP-1) versus Wegovy's single mechanism (GLP-1 only). Clinical trials suggest Mounjaro may produce slightly more weight loss on average (15–21% vs 15%), but individual results vary significantly. Both are once-weekly injections. Your prescriber can advise which suits you better.
What's the difference between off-label and licensed use?
Licensed use means the MHRA has approved the medication for that specific purpose after clinical trials. Off-label means using a licensed medication for a different purpose than it was approved for. Ozempic is licensed for diabetes, not weight loss — so using it for weight loss is off-label and not recommended in the UK.
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.