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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Mounjaro Reviews UK — What You Need to Know
Mounjaro (tirzepatide) is available in the UK through both NHS specialist services and private prescription. While individual experiences vary widely, evidence from NICE approval and clinical trials shows that Mounjaro may help adults with obesity or overweight manage their weight when combined with lifestyle changes. This guide covers real UK eligibility criteria, how the NHS Mounjaro pathway works, what to expect from the prescription process, and how private access differs—so you can make an informed decision about whether this weight loss injection is right for you.
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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 Mounjaro Access and NICE Eligibility in the UK
NICE has approved tirzepatide (Mounjaro) for weight management in UK adults through NHS specialist tier 3 and tier 4 weight management services. Eligibility typically requires a BMI of 30 kg/m² or above, or BMI of 27–29.9 kg/m² with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds often apply (from 27.5 kg/m² onwards), reflecting higher cardiovascular risk at lower weights.
Access is through specialist services, not standard GP prescription. This means referral from your GP to a tier 3 weight management clinic, where a multidisciplinary team assesses whether Mounjaro is appropriate for your individual health profile. Clinical trials showed that adults on Mounjaro lost an average of 15–21% of their body weight over 72 weeks when combined with reduced-calorie diet and increased physical activity—though individual results vary significantly. MHRA monitoring status (▼) means the medication is watched closely for safety, which is standard for newer weight management drugs.
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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.
NHS vs Private Mounjaro Access in the UK
NHS access involves waiting for specialist tier 3 services, which vary by region and can have lengthy waiting lists in some areas. Once prescribed, NHS supply is free on the prescription. Private access is faster—through an online clinical assessment with a UK-licensed prescriber, then dispensed by a GPhC-registered pharmacy—but costs between approximately £129–£280 per month depending on dose. Both routes require a proper clinical assessment; neither provides medication without one. Your GP can advise on NHS availability in your area, or you can explore private options if NHS waiting times are long. Use our free BMI calculator above to check your starting point, and our GLP-1 weight loss calculator to estimate potential outcomes at different Mounjaro doses.
- 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 Mounjaro and Wegovy in the UK?
Both are prescription-only weight loss injections available in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide) is a GLP-1-only agonist. Clinical trials showed Mounjaro may produce slightly higher average weight loss (15–21% vs approximately 15% for Wegovy), but both are effective. Doses and maximum strengths differ. Your prescriber will recommend the most suitable option based on your health profile.
Can I get Mounjaro on the NHS?
Yes, NICE has approved Mounjaro for NHS use through specialist tier 3 weight management services. You'll need a GP referral and meet eligibility criteria (BMI 30+, or 27–29.9 with weight-related health conditions). Availability and waiting times vary significantly by region. Contact your GP or local integrated care board to check NHS provision in your area.
How long does it take to see results from Mounjaro?
Most people begin noticing appetite reduction within the first 1–2 weeks on the starting dose (2.5 mg). Meaningful weight loss typically becomes visible after 4–8 weeks as your dose increases. Clinical trials tracked weight loss over 72 weeks, so Mounjaro is designed for longer-term use. Your progress tracker can help you log changes week by week.
What happens if I stop taking Mounjaro?
If you stop Mounjaro, appetite-suppressing effects typically wear off within days to weeks. Weight regain can occur, which is why ongoing lifestyle changes (diet and activity) are essential. Mounjaro is not a short-term fix; it works best as part of a sustained weight management approach. Discuss any plans to stop with your prescriber.
Are Mounjaro side effects as bad as reviews suggest?
Common side effects include nausea, diarrhoea, constipation, and abdominal discomfort—especially in the first weeks. Most people adapt as their body adjusts; side effects often reduce over time. Serious side effects are rare but require medical attention (severe stomach pain, gallbladder problems, allergic reactions). Individual experiences vary widely. Your prescriber will discuss risks and benefits specific to your health profile.
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.