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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How to Get Monjaro in the UK
Monjaro (tirzepatide) is a prescription-only weekly weight loss injection available in the UK through both NHS specialist services and private prescribing routes. Access depends on your BMI, health conditions, and location. This guide explains NHS eligibility criteria, specialist tier 3 services, and how private online prescribing works, so you can understand your options for accessing this GLP-1 receptor agonist 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 Access to Monjaro — Eligibility and Tier 3 Services
Monjaro is available through NHS tier 3 (specialist) weight management services, not standard GP prescriptions. To access it via the NHS, you typically need:
- BMI of 30 kg/m² or above, or BMI of 27–29.9 with a weight-related health condition (type 2 diabetes, hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease history)
- For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds may apply (BMI 27.5+)
- A referral from your GP to your local tier 3 weight management service
- Assessment and approval by the specialist team
NICE has approved tirzepatide for use within NHS specialist services. However, availability varies significantly by region (by Integrated Care Board), and waiting lists can be substantial—many areas have 6–12 month waits. Contact your GP to ask whether tier 3 services are available in your area and to request a referral.
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.
Private Access to Monjaro — Online Prescribing Route
Many UK adults access Monjaro privately through GPhC-registered online pharmacies. The private route involves:
- An online consultation with a UK-licensed prescriber (doctor or nurse prescriber)
- Clinical assessment of your eligibility and health
- A prescription issued if suitable
- Dispensing by a regulated UK pharmacy
This route does not require NHS referral or tier 3 waiting lists. Costs typically range from £130–£300 per month depending on dose. You can use our free BMI calculator and GLP-1 weight loss calculator above to assess your eligibility and estimate potential results. Always ensure the provider is GPhC-registered and the prescriber is UK-licensed.
- 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's the difference between buying Monjaro on the NHS vs privately?
NHS access is through specialist tier 3 services (free but with waiting lists and regional availability limits). Private access is through online prescribing without NHS referral (faster but costs £130–£300/month). Both routes require a clinical assessment and prescription from a UK-licensed prescriber.
How do I get referred to an NHS tier 3 weight management service for Monjaro?
Ask your GP about tier 3 weight management services in your area. Your GP can refer you if you meet eligibility criteria (BMI 30+ or BMI 27–29.9 with weight-related health conditions). Availability and waiting times vary by region. Contact your local Integrated Care Board for realistic timescales.
Is Monjaro the same as a GLP-1 injection?
No. Monjaro contains tirzepatide, which is a dual GIP and GLP-1 receptor agonist—it activates two pathways, not just one. This dual action may provide greater appetite suppression. Other weight loss injections like Wegovy (semaglutide) activate only the GLP-1 pathway.
Can I switch from another weight loss injection to Monjaro?
Possibly, but only under medical supervision. There is no official conversion chart between tirzepatide and other GLP-1 medications. Any switch must be managed by your prescriber, who will assess your individual response and health. Discuss this with your GP or the prescriber managing your current treatment.
How much weight can I expect to lose with Monjaro?
Clinical trials (SURMOUNT-1) showed average weight loss of 15–21% of body weight over 72 weeks at maximum dose, alongside a reduced-calorie diet and exercise. Individual results vary significantly. Use our GLP-1 weight loss calculator to explore potential outcomes based on your starting weight and 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.