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
Free tracker included with every download this week
Can I Use Mounjaro in the UK?
Whether you can use Mounjaro in the UK depends on your BMI, health conditions, and which route you choose—NHS or private. Mounjaro (tirzepatide) is a prescription-only weight management injection licensed in the UK, but access and costs vary significantly between NHS specialist services and private online prescribing. This guide explains your eligibility, how to access it, and what to expect at each stage.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
UK Eligibility for Mounjaro
You may be eligible for Mounjaro if you're an adult with:
- A BMI of 30 kg/m² or above (obese), OR
- A BMI of 27–29.9 kg/m² (overweight) with at least one weight-related health condition
Weight-related conditions that count include type 2 diabetes, prediabetes, high blood pressure, abnormal blood fats, obstructive sleep apnoea, or a history of heart attack or stroke. If you have South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply—you may be eligible from BMI 27.5 or above. You cannot use Mounjaro if you're under 18, pregnant, breastfeeding, or allergic to tirzepatide. Use our free BMI calculator above to check your personal BMI instantly and see where you fall within these ranges.
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
NHS route: You'll need a GP referral to a tier 3 specialist weight management service. NICE has approved Mounjaro for NHS use, but availability varies hugely by region and waiting lists can stretch months or years. Once approved, NHS prescriptions are free.
Private route: You can access Mounjaro through a UK-licensed prescriber online without NHS referral. After a clinical consultation, a GPhC-registered pharmacy dispenses your prescription. Private costs typically range from £129–£280 per month depending on dose, compared to Wegovy's similar pricing. Our GLP-1 weight loss calculator can help you estimate potential results across different Mounjaro doses before committing.
- 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?
Both are once-weekly weight loss injections available in the UK, but Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) targets GLP-1 only. Clinical trials showed Mounjaro achieved slightly higher average weight loss (~15–21% body weight) compared to Wegovy (~15%), though individual results vary significantly. Both require prescription and clinical assessment.
How much does Mounjaro cost in the UK privately?
Private Mounjaro costs typically range from £129–£280 per month depending on your dose, with each KwikPen containing 4 weeks of supply. Exact pricing varies between GPhC-registered pharmacies. Starting doses (2.5 mg) are usually cheaper than higher maintenance doses (15 mg). Compare costs across providers before choosing.
How long does it take to get Mounjaro on the NHS?
Timelines vary significantly by region. Some specialist services assess patients within weeks; others have waiting lists of 6–12 months or longer. Your GP should be able to tell you typical waiting times in your local area. Private access is usually faster—typically within 1–2 weeks of online consultation approval.
What happens during an online Mounjaro consultation?
A UK-licensed prescriber will review your medical history, current medications, and weight-related health conditions. They'll assess your BMI and eligibility, discuss side effects, and check for any contraindications. If approved, a prescription is issued to a GPhC-registered pharmacy, which ships your first KwikPen to you within days.
Can I switch between NHS and private Mounjaro?
Yes, you can move between routes, but inform both your GP and private prescriber if doing so. If you stop NHS treatment to go private, you may need to reapply to NHS services later. Doses and timing should remain consistent when switching—your prescriber will advise on any adjustments needed.
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.