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
When Was Mounjaro Released in the UK?
Mounjaro (tirzepatide) was first approved by the MHRA in November 2021, initially for type 2 diabetes management. Its use for weight management in UK adults came later, with NICE approval for weight loss following positive clinical evidence. Today, it's available through NHS specialist services and private online prescribing routes. Understanding when Mounjaro became available helps UK patients understand the development of this dual GIP and GLP-1 receptor agonist therapy.
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.
Mounjaro's Timeline and UK Approval Status
November 2021: The MHRA approved tirzepatide (Mounjaro) for treating type 2 diabetes in adults. This marked the first UK authorisation of a dual GIP/GLP-1 receptor agonist — a significant advance over single-mechanism GLP-1 drugs like Wegovy (semaglutide).
2023–2024: Following the SURMOUNT clinical trials demonstrating significant weight loss, NICE reviewed tirzepatide for weight management. NICE approved Mounjaro for use within NHS specialist weight management services for eligible adults with a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, hypertension, or cardiovascular disease.
Mounjaro is now available through NHS tier 3 specialist services and private online prescription routes. The KwikPen injection device comes in doses ranging from 2.5 mg to 15 mg weekly. Our GLP-1 weight loss calculator can help you understand potential outcomes at different doses — though individual results vary considerably.
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.
NHS Access vs Private Prescribing in the UK
NHS route: Mounjaro is available through NHS tier 3 and tier 4 specialist weight management services, typically following referral from your GP. Availability varies significantly by region, and waiting times can be substantial in many areas due to high demand. Your local Integrated Care Board (ICB) determines access criteria and prescribing protocols.
Private route: Mounjaro is available through GPhC-registered online pharmacies following an online clinical assessment by a UK-licensed prescriber. This route offers faster access without NHS waiting lists. Costs typically range from £129–£320 per month depending on dose. Always ensure your chosen provider conducts a proper clinical assessment — prescription medications require professional evaluation, not just a questionnaire.
- 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.
When did Mounjaro first become available in the UK?
Mounjaro received MHRA approval in November 2021 for type 2 diabetes. Weight management approval followed in 2023–2024 after NICE reviewed the SURMOUNT trial evidence showing significant weight loss benefits. It's now available through both NHS specialist services and private prescribing.
How does Mounjaro's approval date compare to Wegovy in the UK?
Wegovy (semaglutide) was approved for weight management in the UK around the same time as Mounjaro's weight management indication. Both are now available, though Mounjaro uses a dual GIP/GLP-1 mechanism while Wegovy is a single GLP-1 agonist. Clinical trial data suggests comparable weight loss outcomes, though individual results vary significantly.
What does NICE approval mean for Mounjaro availability on the NHS?
NICE approval means Mounjaro can be prescribed within NHS tier 3 specialist weight management services to eligible patients. It's not available through standard GP prescribing; referral to a specialist service is required. Availability remains limited by funding and regional variation across ICBs.
Can I get Mounjaro prescribed privately without NHS referral?
Yes. Private online prescribing services can issue Mounjaro prescriptions following an online clinical assessment, without needing NHS referral. This is faster than NHS routes but involves out-of-pocket costs. Always verify the provider is GPhC-registered and conducts proper clinical evaluation.
How do I check if I'm eligible for Mounjaro on the NHS in my area?
Contact your GP to request a referral to your local NHS tier 3 weight management service. Eligibility generally requires BMI ≥30, or ≥27 with weight-related health conditions. Your GP can advise on local waiting times and specific ICB criteria. Our free BMI calculator can help you check your current BMI as a reference point.
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.