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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How to Get Mounjaro in the UK
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK through both NHS specialist services and private online prescribing. To access Mounjaro, you'll need a clinical assessment from a UK-licensed prescriber to confirm it's suitable for your individual health circumstances. This guide explains the different routes to obtaining Mounjaro, eligibility criteria, and what to expect from the prescription process.
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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 vs Private Routes to Mounjaro
In the UK, Mounjaro is available through two main pathways: NHS specialist services and private online prescribing. The NHS route involves referral to a tier 3 or tier 4 specialist weight management service, typically through your GP. However, NHS access varies significantly by region and individual integrated care boards (ICBs) manage their own policies. Many areas have waiting lists of several months to over a year for specialist assessments.
The private route offers faster access without NHS referral. You complete an online health assessment with a UK-licensed prescriber, who reviews your medical history, weight, BMI, and any existing health conditions. If appropriate, they issue a prescription dispensed by a GPhC-registered pharmacy. Private treatment costs range from approximately £129 to £320 per month depending on your dose.
Both routes require the same eligibility criteria: a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, or cardiovascular disease. Lower BMI thresholds may apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage due to higher health risks at lower weights.
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.
What to Expect During Assessment and Prescription
A clinical assessment for Mounjaro includes discussion of your weight history, lifestyle, previous weight loss attempts, and any medical conditions or medications you take. Your prescriber will discuss how Mounjaro works (as a dual GIP and GLP-1 receptor agonist injection), potential side effects including nausea and digestive changes, and realistic expectations around weight loss—clinical trials showed an average loss of 15–21% of body weight, though individual results vary significantly.
Once prescribed, Mounjaro is supplied as pre-filled KwikPen devices. Each pen contains four once-weekly doses. Treatment begins at 2.5 mg weekly, with dose increases every 4 weeks up to a maximum of 15 mg, depending on tolerability and response. You'll inject subcutaneously into your stomach, thigh, or upper arm, rotating injection sites each week. Most people require ongoing prescriptions every 4–12 weeks depending on their dose.
Use our GLP-1 weight loss calculator to estimate potential weight loss at different Mounjaro doses based on clinical trial data. Our BMI calculator can confirm your current BMI and help determine whether you meet the eligibility threshold of 30 or above (or 27–29.9 with weight-related conditions). Tracking your progress is important—our free progress tracker lets you log weight changes, dose levels, and side effects throughout your Mounjaro journey.
- 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 BMI do I need to be prescribed Mounjaro in the UK?
Adults with a BMI of 30 or above are eligible. Those with a BMI of 27–29.9 qualify if they have at least one weight-related health condition such as type 2 diabetes, hypertension, or cardiovascular disease. Lower thresholds (from 27.5) apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. Your prescriber will assess your individual circumstances.
How long does it take to get Mounjaro on the NHS?
NHS waiting times vary significantly by region and local integrated care board policy. Many areas have waiting lists of 6–18 months for specialist weight management services. Private routes typically offer faster access—usually within 1–2 weeks of completing an online assessment. Ask your GP about your local NHS provision.
Can my GP prescribe Mounjaro directly?
NHS prescriptions typically come through specialist tier 3 or 4 weight management services, not standard GP practices. However, private prescriptions can be issued by UK-licensed prescribers following an online consultation, without NHS referral. These prescriptions are dispensed by GPhC-registered pharmacies.
What happens if I switch from another weight loss injection to Mounjaro?
If you're switching from Wegovy or Saxenda to Mounjaro, your prescriber will manage the transition based on your current dose and tolerance. Tirzepatide (Mounjaro) is a dual GIP and GLP-1 agonist while Wegovy is a GLP-1 agonist only, so direct dosing equivalence doesn't apply. Your prescriber will determine the appropriate starting dose for you.
Is Mounjaro available on the NHS as standard weight loss treatment?
NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services, but availability and eligibility criteria vary by region. Not all areas offer it, and access typically requires referral through tier 3 services. Check with your local ICB or GP about availability in your area, or consider private prescribing for faster access.
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.