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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Monjaro Injection — NHS Guide & UK Eligibility
Monjaro is a prescription-only weekly weight loss injection now available through NHS specialist weight management services in the UK. This GLP-1 receptor agonist works by activating natural hormone pathways to help reduce appetite and support weight management. Whether you're eligible depends on your BMI and health circumstances. This guide explains NHS access routes, eligibility criteria, and how Monjaro differs from other weight loss options available in the UK.
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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 Eligibility & Prescribing Criteria
The NHS may prescribe Monjaro (tirzepatide) to adults who meet these criteria:
- BMI of 30 kg/m² or above (obesity), OR
- BMI of 27–29.9 kg/m² (overweight) with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or history of cardiovascular disease
- For patients of South Asian, Chinese, Black African, or Black Caribbean heritage, eligibility may start at a lower BMI threshold of 27.5 or above, as these groups face higher cardiometabolic risk
Monjaro is a dual GIP and GLP-1 receptor agonist — meaning it activates two natural hormone pathways, which may offer stronger appetite regulation than single-mechanism injections. In clinical trials, patients lost an average of 15–21% of their body weight over 72 weeks alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly. You can use our free GLP-1 weight loss calculator to estimate potential weight loss at different doses based on your starting weight.
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 Routes & Getting Monjaro on the NHS
Access to Monjaro through the NHS is managed via tier 3 specialist weight management services. You cannot get Monjaro from your GP directly — you must be referred to a specialist centre by your GP. Waiting times vary significantly by region (ICB area) and can be lengthy — in many parts of the UK, waiting lists exceed six months to over a year. Once referred and assessed as suitable, the specialist team will prescribe and manage your treatment, including dose adjustments every four weeks. Prescriptions are dispensed by NHS pharmacies. If you cannot access NHS specialist services quickly or in your area, private prescription routes are available through GPhC-registered online prescribers following a clinical assessment. Check your BMI and health context using our free BMI calculator above to understand your NHS eligibility 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.
How is Monjaro different from Wegovy in the NHS?
Monjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, whilst Wegovy (semaglutide) activates only GLP-1. In clinical trials, Monjaro achieved slightly higher average weight loss (15–21% vs ~15% for Wegovy). Both are prescription-only and available through NHS tier 3 services, but availability and approval varies by region.
Can I get Monjaro from my GP directly?
No. Monjaro is only prescribed through NHS specialist tier 3 weight management services. Your GP must refer you to your local service for assessment and prescription. You cannot request Monjaro directly from your GP — the specialist team determines eligibility.
What if I can't access Monjaro quickly through the NHS?
If NHS waiting times are long in your area, private online prescribing is available. A UK-licensed prescriber conducts a clinical assessment via consultation, and if suitable, issues a prescription to a GPhC-registered pharmacy. This route is faster but involves cost (typically £150–£320+ per month depending on dose).
Will Monjaro injections be free on the NHS?
Yes. If prescribed through an NHS specialist service, Monjaro is provided free via the NHS, subject to your local prescribing pathway. There are no patient charges (apart from standard prescription fees if applicable to your circumstances).
How often do I inject Monjaro?
Monjaro is a once-weekly injection. You inject the same day each week using a pre-filled KwikPen device. Your prescriber will show you how to inject, and most people find the process straightforward after the first or second dose.
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.