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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Where to Get Mounjaro in the UK: NHS vs Private
If you're considering Mounjaro (tirzepatide) for weight management in the UK, you have two main routes: NHS specialist services or private online prescribing. Both require a clinical assessment and prescription from a UK-licensed healthcare professional. The best option depends on your eligibility, location, budget, and how quickly you need access. This guide compares both pathways and explains how Mounjaro differs from Wegovy, so you can make an informed decision about which is right for you. Use our free GLP-1 weight loss calculator above to explore potential outcomes with either medication.
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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.
NHS vs Private Access: Key Differences
NHS Access: Mounjaro (tirzepatide) is approved by NICE for use within NHS specialist tier 3 and tier 4 weight management services. You'll need a GP referral to a specialist weight management service in your area. Access varies significantly by region — some ICBs (Integrated Care Boards) have established services with waiting lists of 6–18 months, whilst others have limited provision. Once assessed, if eligible, the NHS covers the full cost of the medication. However, availability depends on your local ICB funding decisions.
- Route: GP referral → specialist assessment → NHS prescription
- Cost: Free on NHS if approved
- Speed: Weeks to months (often longer)
- Prescriber: NHS specialist weight management clinician
Private Access: Mounjaro is available through GPhC-registered online pharmacies following an online clinical assessment. No NHS referral needed. Private prescribers can assess and prescribe within days. Costs range from approximately £160–£280 per month depending on dose.
- Route: Online consultation → private prescriber assessment → private pharmacy dispensing
- Cost: Patient pays full cost
- Speed: Days to 1 week
- Prescriber: UK-licensed private prescriber (often GP or independent clinician)
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.
Mounjaro vs Wegovy: Mechanism and Trial Data
Both Mounjaro and Wegovy are licensed for weight management in the UK, but they work differently. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist — it activates two hormone pathways, which is why it's distinct from other weight loss injections. Clinical trials (SURMOUNT-1) showed average weight loss of approximately 15–21% of body weight on the maximum 15mg dose, alongside a reduced-calorie diet and increased physical activity.
Wegovy (semaglutide) activates GLP-1 only. STEP-1 trial data showed average weight loss of approximately 14.9% on the 2.4mg maximum dose under the same conditions. Both are once-weekly injections requiring prescription and clinical assessment. Individual results vary significantly. Your prescriber will recommend the most suitable option based on your health profile, preferences, and access.
- 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.
Can I get Mounjaro on the NHS in the UK?
Yes, Mounjaro (tirzepatide) is approved by NICE for NHS specialist weight management services. You need a GP referral to your local tier 3 or tier 4 service. Availability and waiting times vary significantly by region (ICB). If approved, the NHS covers the full cost, but access is often restricted to those meeting strict BMI and comorbidity criteria.
What's the main difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist (affecting two hormone pathways), whilst Wegovy is a GLP-1 agonist only (one pathway). Clinical trials suggest Mounjaro may produce slightly higher average weight loss, but individual results vary. Both require prescription and clinical assessment. Your prescriber will determine which suits you better.
How long does it take to get Mounjaro privately in the UK?
Through private online prescribing, you can typically have an assessment, prescription, and medication dispensed within 3–7 days. This is significantly faster than NHS routes, which often involve 6–18 month waiting lists for specialist assessment. Private costs are approximately £160–£280 per month depending on dose.
Do I need to be referred by my GP to get Mounjaro privately?
No. Private online prescribing doesn't require a GP referral. You complete an online health questionnaire, a UK-licensed prescriber reviews it, and if suitable, they issue a prescription to a GPhC-registered pharmacy. You'll need a valid NHS number for some providers, but NHS registration is not the same as an NHS prescription.
Is Mounjaro or Wegovy better for weight loss?
Clinical trial data suggests Mounjaro may produce slightly higher average weight loss, but the difference is modest and results vary greatly between individuals. Neither medication is "better" — suitability depends on your health profile, medical history, preferences, and what your prescriber recommends. Both work best alongside a reduced-calorie diet and increased physical activity. Use our GLP-1 weight loss calculator above to explore projected outcomes with each.
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.