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 Inject Mounjaro in Your Thigh: UK Access & Cost Guide
Mounjaro (tirzepatide) can be injected into your upper thigh as one of several injection site options. This UK health guide explains the injection technique, where to access Mounjaro in the UK, and what you can expect to pay. Whether you're considering Mounjaro through the NHS or exploring private prescription options, we'll cover eligibility, costs, and the clinical assessment process you'll need to go through.
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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.
Mounjaro Injection Sites and Thigh Injection Technique
Mounjaro comes as a pre-filled KwikPen device and can be injected into three main sites: your stomach (abdomen), upper thigh, or upper arm. Injecting into your thigh is a straightforward option that many people find convenient for self-administration.
To inject into your thigh:
- Clean the injection area with an alcohol wipe and let it dry
- Pinch the skin gently to create a fold
- Insert the needle at a 90-degree angle (perpendicular to your skin)
- Hold the KwikPen steady for 6 seconds after inserting to ensure full dose delivery
- Rotate your injection site each week to different areas of your thigh, or alternate between thigh and abdomen
Each KwikPen contains 4 pre-filled doses (a 4-week supply). Storage is critical: keep unopened pens in your fridge at 2–8°C, and after first use, you can keep your pen at room temperature (below 30°C) for up to 30 days. Always check the expiry date before injecting.
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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
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Mounjaro Costs & NHS vs Private Access in the UK
NHS access: Mounjaro (tirzepatide) has been approved by NICE for NHS specialist weight management services, but access is limited to tier 3 and tier 4 specialist services. You'll need a GP referral, and availability varies significantly by region and ICB. Waiting lists can be lengthy in many areas.
Private prescription costs: Through private online prescribing, Mounjaro typically costs £129–£280 per month depending on your dose and the provider. You'll need an online clinical assessment with a UK-licensed prescriber before a prescription is issued. Private access doesn't require NHS referral but costs are out-of-pocket. Once prescribed, your medication is dispensed by a GPhC-registered pharmacy. Use our GLP-1 weight loss calculator to estimate potential outcomes at different doses.
What to expect with private prescription: You'll complete an online health questionnaire and have a consultation with a UK-licensed doctor or nurse prescriber. They'll assess your eligibility based on your BMI, health history, and any weight-related conditions. If approved, a prescription is issued and sent to a pharmacy for dispensing. The entire process typically takes 1–3 working days. Your prescriber will recommend a starting dose (usually 2.5 mg) and outline a dose escalation schedule. You'll receive guidance on injection technique, storage, and when to increase your dose. Most providers offer follow-up support via phone or messaging.
- 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.
Can I inject Mounjaro anywhere on my thigh?
Yes, you can inject into either thigh and any area of the upper thigh. Rotate your injection site each week to avoid irritation and lipohypertrophy (thickened fatty tissue). You can also alternate between your thighs, abdomen, or upper arms to spread injection sites throughout the month.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs range from approximately £129–£280 per month depending on your dose (higher doses cost more). This is a one-off payment per delivery; there are no hidden additional costs if you're using a GPhC-registered provider. NHS access is free but requires specialist referral and faces long waiting lists.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro has a maximum dose of 15 mg weekly; Wegovy's maximum is 2.4 mg weekly. Clinical trials showed Mounjaro may produce slightly greater average weight loss, but individual results vary significantly.
Do I need a clinical assessment before being prescribed Mounjaro?
Yes, always. Whether accessing through NHS specialist services or private prescription, you must have a clinical assessment by a UK-licensed prescriber. They'll review your BMI, medical history, current medications, and any weight-related conditions to determine eligibility and safety before issuing a prescription.
How do I access Mounjaro through the NHS?
Ask your GP for a referral to your local tier 3 specialist weight management service. You'll need a BMI of 30 or above (or 27+ with weight-related health conditions). NHS access is free but subject to regional availability and waiting lists. Private prescription offers faster access but is not funded by the NHS.
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.