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
Free tracker included with every download this week
Where Should You Inject Mounjaro for Best Results?
Mounjaro (tirzepatide) injections work effectively when given in the correct locations on your body, though the specific injection site doesn't significantly affect weight loss results. What matters most is rotating injection sites each week and choosing accessible areas that are comfortable for you. This guide explains recommended Mounjaro injection sites, how to access tirzepatide in the UK, and what you can expect from the prescription process.
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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 Injection Technique
Recommended Mounjaro injection sites are areas with a good layer of fatty tissue beneath the skin. The three approved locations are the stomach (abdomen), upper thigh, and upper arm. The stomach (abdomen) is the most commonly used site — most people inject around the belly area, typically 5 cm away from the belly button. The upper thigh is equally effective and works well if you prefer more privacy or easier access without undressing. The upper arm is also approved but typically requires assistance from another person to administer safely.
- Rotate your injection site each week to prevent irritation or lipohypertrophy (fatty lumps)
- Ensure the area is clean and dry before injecting
- Allow your Mounjaro KwikPen to reach room temperature (15–30 minutes out of the fridge) before injecting
- Inject slowly over 5–10 seconds and wait 10 seconds before removing the needle
- Check the pen window — you should see a grey plunger moving during injection
The actual site location doesn't materially affect weight loss outcomes — the medication works systemically regardless of where you inject. Focus on comfort, accessibility, and consistent site rotation for best tolerance and to minimise injection site reactions.
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.
Accessing Mounjaro in the UK: NHS and Private Routes
In the UK, Mounjaro is available through two main routes. The NHS route involves referral from your GP to a tier 3 specialist weight management service. NICE has approved tirzepatide for NHS use, but availability varies significantly by region and waiting lists can be months or longer in many areas. Your GP will assess whether you meet eligibility criteria (BMI 30+ or 27+ with weight-related health conditions).
The private route offers faster access without NHS referral. A UK-licensed prescriber conducts an online clinical assessment, and if appropriate, issues a prescription dispensed by a GPhC-registered pharmacy. Private Mounjaro costs typically range from £130–£250 per month depending on your dose, with 5 mg doses at the lower end and higher doses (10–15 mg) costing more. Most private providers offer flexible monthly or quarterly payment plans.
Online consultation process: You'll complete a health questionnaire covering your weight, height, medical history, current medications, and weight loss goals. A prescriber reviews this and conducts a brief video or phone consultation to assess suitability. If approved, a prescription is issued and sent directly to the pharmacy, which dispatches your KwikPens via courier. This entire process typically takes 2–5 working days. Use our free GLP-1 weight loss calculator above to explore potential outcomes with Mounjaro at different doses, and try our BMI calculator to check your current position against NHS eligibility criteria.
- 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.
Does it matter where on the stomach I inject Mounjaro?
No — any area of the stomach with adequate fatty tissue is appropriate. Most people inject around the sides or lower abdomen, at least 5 cm away from the belly button. Rotate between slightly different spots each week. The specific location doesn't affect weight loss efficacy; comfort and site rotation matter most.
Can I inject Mounjaro in the same spot twice?
Not recommended. Injecting in the same location repeatedly increases risk of lipohypertrophy (lumps), injection site reactions, and uneven absorption. Rotate to a different injection site each week — this minimises irritation and maintains consistent medication absorption.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £130–£250 per month depending on dose. A 5 mg weekly dose (starting/maintenance for some) costs less than higher doses like 10 mg or 15 mg. Many private providers offer upfront pricing, monthly subscriptions, or quarterly payment plans. Costs vary between providers, so it's worth comparing.
What's the difference between NHS and private Mounjaro access?
NHS access is free but requires GP referral to specialist services and can involve long waiting lists (weeks to months or longer in some regions). Private access is faster (2–5 days typically) and doesn't require NHS referral, but you pay monthly. Both routes require clinical assessment; both dispense the same medication at the same doses.
Do I need a GP's permission to get Mounjaro privately?
No — you can access Mounjaro privately without GP involvement. However, it's good practice to inform your GP that you're taking a weight loss injection, especially if you take other medications. Your GP can monitor your progress and check for any interactions with your current medications.
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.