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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Where to Inject Mounjaro: Sites, Access & Cost in the UK
Mounjaro (tirzepatide) is injected into specific areas of your body each week using a pre-filled KwikPen device. In the UK, you can access Mounjaro through NHS specialist weight management services or private online prescribing. This guide explains the injection sites, how to access Mounjaro, and what you can expect to pay. Understanding your options helps you make an informed decision about weight management treatment that suits your circumstances.
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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 Explained
Mounjaro is administered once weekly via subcutaneous injection (under the skin). The stomach area (abdomen) is the most commonly used injection site — it's easiest to reach and inject yourself. The upper thigh is the second most common choice, offering good accessibility for self-injection. Your upper arm can also be used, though this typically requires assistance from another person to inject safely and comfortably.
- Abdomen: Inject at least 2 inches away from your belly button. Avoid scar tissue or bruised areas.
- Thigh: Use the outer front or outer side of your thigh. Rotate between left and right leg each week.
- Upper arm: Back of the arm, between shoulder and elbow. Usually requires assistance.
Rotate your injection site each week to reduce irritation and bruising. You can reuse the same area, but not the same spot within 2 weeks. Store your KwikPen in the refrigerator at 2°C to 8°C until use, then bring to room temperature 15–30 minutes before injecting for greater comfort.
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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.
Accessing Mounjaro in the UK: NHS vs Private
NHS Access: NICE has approved tirzepatide for NHS use within specialist tier 3 weight management services. Your GP can refer you to your local specialist service, though waiting times vary significantly by region — some areas have months-long waiting lists. Once assessed, the NHS will prescribe and supply Mounjaro at no charge beyond your prescription fee.
Private Access: You can obtain Mounjaro privately through UK-licensed online prescribers. Following an online consultation where your eligibility is assessed, a prescription is issued if appropriate and dispensed by a GPhC-registered pharmacy. Private Mounjaro typically costs £150–£300+ per month depending on your dose. At the maximum 15 mg dose, costs are higher than lower doses. No NHS referral is needed for the private route, and treatment can begin within days of assessment.
- 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 are the exact injection sites for Mounjaro?
Mounjaro is injected under the skin (subcutaneously) into the abdomen, upper thigh, or upper arm. The abdomen is most commonly used for self-injection. Rotate your injection site each week and avoid injecting within 2 weeks of the previous spot in the same area to prevent bruising and irritation.
How much does Mounjaro cost in the UK?
Private Mounjaro costs approximately £150–£320 per month depending on your dose level. Starting doses (2.5–5 mg) are at the lower end; maximum doses (15 mg) are at the higher end. NHS access is free (prescription fee only), but requires referral to a specialist weight management service and can involve significant waiting times.
Can I get Mounjaro on the NHS in the UK?
Yes, NICE has approved tirzepatide for NHS specialist weight management services. Your GP can refer you to your local tier 3 service for assessment. However, NHS availability and waiting times vary considerably by region. Some areas have lengthy waiting lists; others may have limited availability depending on your ICB's funding.
How do I access Mounjaro privately in the UK?
Book an online consultation with a UK-licensed prescriber through registered online services. A clinical assessment is completed to establish your eligibility (BMI and health factors). If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. Treatment typically begins within days.
Is Mounjaro the same as Wegovy for injection sites?
Both Mounjaro and Wegovy use the same injection sites (abdomen, thigh, upper arm) and are both once-weekly injections. However, they are different medications — Mounjaro is a dual GIP/GLP-1 agonist, whilst Wegovy (semaglutide) is a GLP-1 agonist only. Your prescriber will assess which is more suitable for your individual circumstances.
Ready to take control of your weight loss journey?
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