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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Getting Mounjaro on an NHS Prescription in the UK
Mounjaro (tirzepatide) is now approved by NICE for NHS use in specialist weight management services across the UK. However, NHS access is limited to tier 3 and tier 4 weight management services — it is not available from your standard GP practice. This guide explains NHS eligibility criteria, how the specialist services work, and what the approval means for you. Use our free BMI calculator to check your starting point, then explore whether you might qualify for NHS-prescribed weight loss treatment.
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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 and Specialist Tier 3 Services
NICE approved Mounjaro (tirzepatide) for NHS use in March 2024 within specialist weight management services. However, access is not automatic — you must be referred to a tier 3 or tier 4 specialist service, typically through your GP.
You may be eligible if you:
- Have a BMI of 30 kg/m² or above, OR a BMI of 27–29.9 with weight-related health conditions (type 2 diabetes, prediabetes, high blood pressure, high cholesterol, sleep apnoea, or cardiovascular disease history)
- Are of South Asian, Chinese, Black African, or Black Caribbean heritage with a BMI of 27.5 or above (lower thresholds apply due to higher health risks)
- Have completed a tier 2 intervention (such as the NHS Weight Loss Plan) without sufficient results
- Are motivated to combine medication with diet and lifestyle changes
Access varies significantly by region. Some ICBs (Integrated Care Boards) have waiting lists of several months or longer. Your GP will assess your suitability and refer you if appropriate to the nearest specialist service. The Mounjaro KwikPen device comes pre-filled with four weekly doses and uses a unique dual GIP and GLP-1 mechanism, which differs from older weight loss injection approaches.
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 vs Private Routes for Mounjaro in the UK
NHS route: Free at the point of use, but requires GP referral, specialist assessment, and availability through your local tier 3 service. Waiting times can be significant (weeks to months in many areas). Once approved, you receive Mounjaro doses at no cost.
Private route: Access without waiting lists through a UK-licensed prescriber via online consultation. Faster to start but costs approximately £129–£320 per month depending on dose. You can track your progress using our free progress tracker whether accessing medication via NHS or private routes. Both routes require the same clinical assessment — your health history, BMI, and weight-related conditions are evaluated before prescription.
- 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.
Do I need to see my GP first to get Mounjaro on the NHS?
Yes. Your GP must refer you to a specialist tier 3 weight management service for assessment. You cannot request Mounjaro directly from your GP practice — it is only available through specialist services. Your GP will evaluate whether referral is appropriate based on your BMI, health conditions, and previous weight loss efforts.
What is the difference between tier 3 and tier 4 NHS weight management services?
Tier 3 services are specialist multidisciplinary teams (doctors, nurses, dietitians, psychologists) offering intensive behaviour change support plus medication. Tier 4 services include bariatric surgery and are for more severe obesity. Mounjaro is typically prescribed at tier 3 level, though tier 4 services may also use it alongside other treatments.
How long is the NHS waiting list for Mounjaro?
Waiting times vary significantly by region (ICB). Some areas have waiting lists of 3–6 months; others may be longer. You can ask your GP about typical waiting times in your local area when requesting referral. Availability also depends on whether your local tier 3 service has been allocated funding for tirzepatide prescriptions.
Can I switch from private Mounjaro to NHS prescriptions?
Potentially, but this requires specialist assessment through your local NHS tier 3 service. If you are already on a private Mounjaro prescription and wish to transfer to NHS, discuss this with your GP or contact your local specialist service. They will assess whether continuation is clinically appropriate and whether they have capacity.
What happens after NICE approval — will Mounjaro be available in all GP practices?
No. NICE approval means NHS funding is available, but Mounjaro remains a specialist-initiated medication. It is only prescribed through tier 3 weight management services, not standard GP practices. Your local ICB may also set their own access criteria, so availability is not uniform across the UK.
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.