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 Injection Sites and UK Access Guide
Mounjaro (tirzepatide) is injected once weekly into specific body areas, but accessing this prescription-only weight loss injection in the UK depends on whether you use the NHS or private route. This guide covers where to inject, how to get a prescription, and what costs you can expect. We'll explain the differences between NHS specialist services and private online prescribing, so you can understand your options and make an informed decision about whether this medication is right for you.
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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.
Where to Inject Mounjaro and UK Access Routes
Injection sites: Mounjaro is administered as a once-weekly subcutaneous injection (under the skin) using a pre-filled KwikPen device. The recommended injection sites are the stomach (abdomen), upper thigh, or upper arm. Most people start with the stomach as it's easiest to self-inject. You should rotate your injection site each week to prevent skin irritation and lipohypertrophy (thickened tissue). Never inject into areas where the skin is tender, bruised, or scarred.
In the UK, accessing Mounjaro depends on your route: NHS access is through tier 3 specialist weight management services (requires GP referral, long waiting lists in many areas), or private access via a UK-licensed prescriber following an online clinical assessment. The weekly weight loss injection is the same medication either way — the difference is how you access it and who prescribes it.
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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: Cost, Access, and Timeline
NHS route: Free at the point of use (standard prescription charge applies, currently £9.90 in England if eligible). However, access is limited to specialist services, and waiting lists can exceed 12 months in some areas. Not all regions fund tirzepatide equally. Your GP must refer you to your local tier 3 service, which will assess your eligibility.
Private route: Costs range from approximately £129–£320 per month depending on dose and provider. You access a UK-licensed prescriber through an online consultation (typically £15–£50), and if approved, your prescription is dispensed by a GPhC-registered pharmacy. No waiting lists — you can start treatment within days. Private prescribing is faster but requires you to manage ongoing costs. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses.
---COL_J_ALTERNATIVE---NHS route: Free at the point of use (standard prescription charge applies, currently £9.90 in England if eligible). However, access is limited to specialist services, and waiting lists can exceed 12 months in some areas. Not all regions fund tirzepatide equally. Your GP must refer you to your local tier 3 service, which will assess your eligibility.
Private route: Costs range from approximately £129–£320 per month depending on dose and provider. You access a UK-licensed prescriber through an online consultation (typically £15–£50), and if approved, your prescription is dispensed by a GPhC-registered pharmacy. No waiting lists — you can start treatment within days. Private prescribing is faster but requires you to manage ongoing costs. Calculate your BMI and discuss your eligibility with your GP or a licensed prescriber before starting 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.
How much does Mounjaro cost privately in the UK?
Private Mounjaro typically costs £129–£320 per month depending on the dose. Starting doses (2.5–5 mg) are usually at the lower end; higher maintenance doses (10–15 mg) cost more. Online consultation fees are typically £15–£50 extra. The exact cost varies by provider and stock availability, so compare before committing.
Can I get Mounjaro free on the NHS?
Yes, Mounjaro is available free on the NHS through specialist tier 3 weight management services. However, access is limited and waiting lists are often very long (6–18 months in many areas). You must be referred by your GP and meet specific eligibility criteria. Availability varies significantly by region.
What's the difference between NHS and private Mounjaro?
The medication is identical. The differences are: NHS is free but has limited access and long waits; private costs more but is faster (days to start). Both require a prescription from a UK-licensed prescriber. Both assess eligibility. Choose based on your timeline, budget, and local NHS availability.
How do I get a private Mounjaro prescription in the UK?
Complete an online consultation with a registered UK prescriber (typically via an online clinic). You'll answer health questions about your BMI, medical history, and medications. If approved, your prescription is sent to a GPhC-registered pharmacy for dispensing. The entire process usually takes 2–7 days.
Is Mounjaro the same as Wegovy for weight loss?
Both are prescription-only weight loss injections, but they're different medications. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials show similar average weight loss (~15–21%), but individual results vary. A prescriber can help you decide which suits you.
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.