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 in the UK: NHS Access and Prescribing Guide
Mounjaro (tirzepatide) is a prescription-only weight management injection licensed in the UK for adults with obesity or overweight with weight-related health conditions. The medication works as a dual GIP and GLP-1 receptor agonist, supporting appetite regulation and weight loss when used alongside lifestyle changes. Access in the UK is available through NHS specialist weight management services or private online prescribing. Understanding how Mounjaro works within the UK healthcare system, including eligibility criteria and prescribing pathways, helps you make informed decisions about whether this treatment might be suitable for you.
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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.
NHS Eligibility and NICE Guidance for Mounjaro
NICE has approved tirzepatide (Mounjaro) for use in NHS specialist weight management services, though access varies significantly by region and ICB (integrated care board). You may be eligible for Mounjaro through the NHS if you have:
- A BMI of 30 kg/m² or above, or
- A BMI of 27–29.9 kg/m² alongside at least one weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or cardiovascular disease history)
- For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply (27.5 and above)
NHS access is through tier 3 specialist weight management services, not standard GP prescription. Your GP can refer you, but waiting times for specialist services can extend several months to over a year in many areas. The MHRA has approved Mounjaro with additional monitoring (Black Triangle status), meaning post-market surveillance is ongoing.
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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
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS vs Private Routes for Accessing Mounjaro in the UK
NHS route: Free on prescription through tier 3 specialist weight management services, but requires GP referral and specialist assessment. Availability and waiting times vary significantly by region. Once prescribed, the medication is dispensed at NHS cost.
Private route: Available through GPhC-registered online pharmacies following a UK-licensed prescriber assessment. No NHS referral needed, no waiting lists, but costs typically range from £129–£280 per month depending on dose. Private prescribers assess eligibility during a consultation and issue a prescription if appropriate. Both routes require a clinical assessment; Mounjaro is not available to purchase without a prescription from a licensed prescriber.
- 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.
What is the difference between Mounjaro and the diabetes version of tirzepatide?
Mounjaro is tirzepatide specifically licensed for weight management in UK adults. Tirzepatide is also used at lower doses for type 2 diabetes under the brand name Mounjaro or other names, but Mounjaro at the licensed weight management doses (up to 15 mg) is distinct from diabetes treatment. Always use the branded formulation prescribed by your healthcare provider.
How long does it take to see weight loss results with Mounjaro on the NHS?
Clinical trials showed gradual weight loss over weeks, with more significant results visible after 12–16 weeks of treatment. Individual results vary significantly. Results achieved alongside reduced-calorie diet and increased physical activity. Your prescriber will monitor progress at regular intervals and adjust dose if needed.
Can I get Mounjaro without a GP referral in the UK?
Yes. Through the NHS route, you need a GP referral to tier 3 services. Through private prescribing, you do not need a GP referral—you can access a UK-licensed prescriber online for assessment. Both routes require a clinical prescription; Mounjaro is prescription-only and cannot be purchased without one.
What does the MHRA Black Triangle (▼) status mean for Mounjaro?
The Black Triangle indicates Mounjaro is subject to additional monitoring for safety. This is standard for newer medications and does not mean the drug is unsafe—it means the MHRA is actively monitoring real-world safety data. Report any unexpected side effects to your prescriber or via the Yellow Card scheme.
Is Mounjaro available on the NHS in my area?
NICE has approved Mounjaro, but availability varies by ICB and region. Some areas have well-established specialist services; others have limited or no Mounjaro prescribing. Ask your GP about tier 3 weight management services in your area or contact your local ICB directly to check availability and waiting times.
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.