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 Can I Inject Mounjaro in the UK
Mounjaro (tirzepatide) is injected once weekly under the skin at specific body sites. In the UK, you can access Mounjaro through NHS specialist weight management services or privately through online prescribers following clinical assessment. The medication comes in a pre-filled KwikPen device, making self-injection straightforward. Understanding where to inject, how to access it, and what it costs are essential first steps if you're considering this treatment. Use our GLP-1 weight loss calculator to explore potential outcomes, and our BMI calculator to check your eligibility based on current guidelines.
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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.
Mounjaro Injection Sites and Access Routes
Mounjaro is administered as a subcutaneous injection — under the skin, not into muscle or vein. You can inject at three main sites: the stomach (abdomen), upper thigh, or upper arm. Most people find the stomach easiest to self-inject. Each injection site should be rotated weekly to avoid irritation. The KwikPen device is pre-filled with your prescribed dose and requires no mixing or assembly.
- Abdomen: Most common choice; easy to access and inject yourself
- Upper thigh: Second choice; good for rotation
- Upper arm: Requires assistance from another person
- Storage: Keep unopened pens refrigerated at 2–8°C; after first use, can be stored at room temperature (below 30°C) for up to 30 days
In the UK, you access Mounjaro through two main routes: NHS specialist services (tier 3 weight management) or private online prescribing. NHS access requires GP referral and involves assessment through specialist services, though waiting lists vary significantly by region. Private access is faster and doesn't require NHS referral — you complete an online clinical assessment with a UK-licensed prescriber, receive a prescription if suitable, and have it dispensed by a GPhC-registered pharmacy.
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.
Mounjaro Cost and Private Prescription Process
Private Mounjaro costs in the UK typically range from £150 to £300+ per month depending on your dose and provider. Starting doses (2.5 mg) are usually cheaper than maintenance doses (15 mg). Costs are paid privately — not covered by the NHS on the private route. The online prescription process is straightforward: you complete a health questionnaire, a UK-licensed prescriber reviews your eligibility (based on BMI and health factors), and if approved, a prescription is issued to a pharmacy. Eligibility generally requires a BMI of 30+, or 27+ with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease.
- Private prescriptions: typically £150–£300/month depending on dose level
- NHS route: free if approved by specialist services (but waiting lists can be very long)
- Prescription-only: always requires clinical assessment before dispensing
- Online consultation: usually takes 24–48 hours for prescriber review and approval
The NHS route offers free Mounjaro but typically involves referral to tier 3 specialist weight management services, clinical assessment, and potentially significant waiting times (months to years in some areas). Access varies by region — your local ICB (Integrated Care Board) determines availability. The private route is faster (prescription within 48 hours), doesn't require NHS referral, but requires payment. Both routes require clinical assessment to confirm you meet eligibility criteria. If you have a BMI of 30 or above, or 25–29 with weight-related conditions, you may qualify. Your GP can discuss NHS options, or you can explore private prescribing independently. Our GLP-1 weight loss calculator helps you understand potential dose progression and estimated outcomes to inform your decision.
- 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 three places I can inject Mounjaro?
You can inject Mounjaro into the stomach (abdomen — most common), upper thigh, or upper arm. Rotate injection sites weekly to prevent irritation and discomfort. The abdomen is usually preferred for self-injection because it's easiest to access.
How much does a private Mounjaro prescription cost in the UK?
Private Mounjaro typically costs £150–£300+ per month, depending on your dose. Starting doses (2.5 mg) are cheaper than higher maintenance doses (15 mg). Costs vary by provider. NHS access is free if approved through specialist services, but waiting lists can be very long.
Can I get Mounjaro on the NHS in the UK?
Yes, but access is through specialist tier 3 weight management services, usually requiring GP referral and clinical assessment. Availability and waiting times vary significantly by region. NICE has approved tirzepatide for NHS use, but not all areas have the same capacity or availability.
What is a KwikPen and how do I use it?
The KwikPen is a pre-filled injection pen for Mounjaro. It requires no mixing or assembly — you simply dial your dose (your pharmacist will tell you which number), inject under the skin at your chosen site, and dispose of it safely. Each pen contains 4 weeks of doses.
How long does the online private prescription process take?
Most online prescribers review health questionnaires and issue prescriptions within 24–48 hours if you're clinically suitable. The pharmacy then dispenses your Mounjaro, often within a few days. The entire process is typically completed within a week.
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.