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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Can You Get Mounjaro On The NHS In The UK?
Yes, Mounjaro (tirzepatide) is available on the NHS for weight management, but access is through specialist tier 3 weight management services, not standard GP prescription. NICE has approved tirzepatide for use within NHS weight management programmes. However, NHS availability varies significantly by region, and waiting lists can be very long in many areas. Private prescription access is also available as an alternative. This guide explains NHS eligibility, the referral pathway, and how Mounjaro compares to Wegovy on the NHS.
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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 vs Private Access For Mounjaro And Wegovy
NHS route: Mounjaro is available through specialist NHS tier 3 weight management services. To access it, you need a referral from your GP to your local Integrated Care Board (ICB) weight management service. Once referred, you'll have a clinical assessment to determine if Mounjaro is suitable. NHS Mounjaro is free at the point of prescribing, but availability and waiting times vary dramatically by region—some areas have waiting lists of 12–24 months, whilst others may have shorter waits.
Private route: Mounjaro via private prescription is available without NHS referral through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. This route typically offers faster access (days to weeks) but involves costs, ranging from approximately £129–£320 per month depending on the Mounjaro dose. The injectable KwikPen format is the same whether NHS or private.
Both routes require a clinical assessment to ensure you meet eligibility criteria for weight management medication.
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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.
Mounjaro vs Wegovy: Mechanism, Trials, And Individual Suitability
Mounjaro and Wegovy are both once-weekly injections approved in the UK for weight management, but they work differently. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist—it activates two hormone pathways. Wegovy (semaglutide) is a GLP-1 receptor agonist only. Clinical trials showed Mounjaro achieved average weight loss of approximately 15–21% body weight (SURMOUNT trial), whilst Wegovy achieved approximately clinically studied weight loss (STEP trial). However, individual results vary significantly. Your prescriber will assess which medication is more suitable based on your health profile, medical history, and any contraindications. Both require dose titration starting from a low dose and increasing weekly or monthly. Neither is "better"—suitability is individual.
- 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 are the NHS eligibility criteria for Mounjaro?
You may be eligible for NHS Mounjaro if you have a BMI of 30 kg/m² or above, or BMI of 27–29.9 with at least one weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, or cardiovascular disease history). South Asian, Chinese, Black African, or Black Caribbean adults may have lower BMI thresholds. Your GP can assess your eligibility during a referral conversation.
How long are NHS waiting lists for Mounjaro?
Waiting times vary significantly by region in the UK. Some specialist weight management services have waiting lists of 12–24 months, whilst others may have shorter waits. Contact your local NHS weight management service or ask your GP about typical waiting times in your area. Private prescription may offer faster access if NHS waiting times are long.
Can I switch between Mounjaro and Wegovy on the NHS?
Switching between medications is possible but requires your prescriber's decision and clinical reassessment. There is no official conversion chart between Mounjaro and Wegovy doses—any switch must be managed by your prescriber. Some NHS services may have restrictions on switching based on local guidelines and budget constraints.
What's the difference between Mounjaro dose titration and maximum dose?
Mounjaro dose titration means gradually increasing your dose weekly: starting at 2.5 mg, then 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg (the maximum dose). You stay on each dose for at least 4 weeks before increasing. Not everyone reaches the maximum dose—your prescriber will find the dose that works for you.
Does Mounjaro side effects profile differ from Wegovy on NHS?
Both medications have similar common side effects: nausea, diarrhoea, constipation, and stomach pain. These often improve over time. Mounjaro may have a slightly different side effect balance due to its dual mechanism, but individual responses vary significantly. Any side effects should be reported to your prescriber immediately, especially severe stomach pain.
Ready to take control of your weight loss journey?
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