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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Weight Loss Injection Mounjaro: NHS Access in the UK
Mounjaro (tirzepatide) is a prescription-only weight loss injection licensed in the UK for adults with obesity or overweight with weight-related health conditions. It's a once-weekly injectable medication that works as a dual GIP and GLP-1 receptor agonist, helping regulate appetite and support feeling fuller after meals. The NHS has approved tirzepatide through NICE guidance, though access varies significantly by region. This guide explains NHS eligibility, how specialist services work, and what to expect if you're considering this weekly weight loss injection as part of your health journey.
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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 Tier 3 Specialist Services
NHS access to Mounjaro is managed through tier 3 specialist weight management services, not standard GP prescription. You'll typically need a referral from your GP to your local integrated care board (ICB) weight management service. Eligibility criteria include: a BMI of 30 kg/m² or above, or BMI of 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, hypertension, dyslipidaemia, sleep apnoea, or cardiovascular disease history. For adults of South Asian, Chinese, Black African, or Black Caribbean backgrounds, lower thresholds may apply (BMI 27.5 or above) due to increased health risks at lower weights.
The NHS NICE guidance recognises tirzepatide as an effective option within specialist weight management programmes. Clinical trial data (SURMOUNT-1) showed average weight loss of approximately 20.9% body weight at the maximum 15 mg dose over 72 weeks, alongside reduced-calorie diet and increased physical activity. Individual results vary considerably. Waiting times for NHS tier 3 services can be substantial in many regions—some areas have waiting lists of 12 months or longer.
Use our free GLP-1 weight loss calculator to explore estimated weight loss projections at different Mounjaro doses, and try our BMI calculator to check your current BMI against NHS eligibility thresholds.
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 Access Routes in the UK
Two main routes exist for Mounjaro access in the UK: NHS tier 3 specialist services (free at point of use but with eligibility assessment and often long waiting times) and private online prescribing (faster access but not free, typically £150–£320 per month depending on dose). NHS prescribing follows NICE guidance and involves a full clinical assessment, dietitian support, and ongoing monitoring within the specialist service. Private prescribing through GPhC-registered online pharmacies offers faster turnaround and no waiting list, but you pay privately and receive less ongoing clinical support.
Both routes require a clinical assessment before prescription. If you're interested in exploring weight loss options, speak with your GP about NHS referral, or consider private online assessment if you prefer quicker access. Track your progress with our free progress tracker once you begin treatment.
- 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.
Is Mounjaro available on the NHS in the UK?
Yes, Mounjaro (tirzepatide) is approved by NICE for NHS use within tier 3 specialist weight management services. Access is through your GP with referral to your local ICB service. Availability and waiting times vary significantly by region. Many areas have substantial waiting lists. Private access is also available outside the NHS.
What is the NHS BMI eligibility for Mounjaro?
NHS eligibility is BMI 30 or above, or BMI 27–29.9 with weight-related health conditions (diabetes, hypertension, sleep apnoea, cardiovascular disease). For South Asian, Chinese, Black African, and Black Caribbean adults, eligibility thresholds are lower (BMI 27.5 or above). Your GP can assess whether you meet criteria.
How long is the NHS waiting list for Mounjaro?
Waiting times vary by region. Some areas have waits of 3–6 months, others 12+ months. Contact your local ICB weight management service for specific information. Private online prescribing offers faster access if NHS waiting times are lengthy in your area.
What's the difference between NHS and private Mounjaro in the UK?
NHS Mounjaro is free but requires GP referral, clinical assessment, and follows NICE guidelines with ongoing specialist support. Private Mounjaro is faster to access (no waiting list) but costs approximately £150–£320 monthly and is dispensed by private pharmacies following online clinical assessment.
How much weight loss can I expect with Mounjaro on the NHS?
Clinical trials showed average weight loss of approximately 15–21% of body weight over 72 weeks alongside diet and exercise changes. Individual results vary significantly based on dose, adherence, and lifestyle factors. Your specialist team will discuss realistic expectations for your circumstances. ```
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.