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 Much Does Mounjaro 12.5mg Cost in the UK?
Mounjaro 12.5mg is the second-highest maintenance dose of tirzepatide available in the UK, and cost varies significantly depending on whether you access it through the NHS or privately. At the 12.5mg dose, you're typically looking at private costs of £180–£280 per month, though this can vary by provider. NHS access is free but involves specialist referral and often lengthy waiting lists. This guide explains both routes, what to expect, and how the 12.5mg dose compares to other options available to UK adults seeking prescription weight management support.
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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.
Private Prescription Costs for Mounjaro in the UK
In the private sector, Mounjaro 12.5mg costs approximately £180–£280 per month depending on your prescriber and pharmacy. Each pre-filled KwikPen contains 4 weeks of doses (one injection weekly), so a monthly supply is standard. Some providers offer discounts for paying upfront for 3 or 6 months, which can reduce the per-month cost to around £150–£240. These costs include the clinical assessment, prescription, and medication. To access private Mounjaro, you'll undergo an online consultation with a UK-licensed prescriber who assesses your eligibility based on BMI, health conditions, and medication history. If approved, a prescription is issued to a GPhC-registered pharmacy for dispensing. You can check your eligibility using our free GLP-1 weight loss calculator, which estimates potential results at different doses including 12.5mg. The entire process typically takes 1–2 weeks from initial consultation to first delivery.
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.
NHS Access vs Private: What's the Difference?
On the NHS, Mounjaro is free once prescribed, but access is strictly through specialist tier 3 or tier 4 weight management services. Your GP must refer you to a specialist weight management clinic in your area, and eligibility criteria apply (usually BMI 30 or above, or BMI 27+ with weight-related conditions). NHS waiting lists for specialist services vary dramatically by region—some areas have waits of 6–18 months. Private access bypasses waiting lists but costs £180–£280 monthly. NHS prescriptions are managed by specialists who monitor you regularly. Private prescriptions are issued following online assessment and can be managed through either the private provider or your own GP. Check whether your local ICB (Integrated Care Board) funds Mounjaro—NICE approval exists, but regional commissioning varies. Use our BMI calculator to check your starting point and discuss NHS eligibility with your GP.
- 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.
Is Mounjaro 12.5mg the maximum dose I can take?
No. Mounjaro's maximum licensed dose is 15mg weekly. The 12.5mg dose is the second-highest step in the titration schedule. Your prescriber will determine the right dose for you based on your response and tolerability. Dose increases typically happen every 4 weeks.
Why is Mounjaro private prescription more expensive than some other weight loss injections?
Costs vary by provider and dose. Mounjaro is a dual GIP/GLP-1 agonist (different mechanism to some alternatives), manufactured by Eli Lilly, and prices reflect prescriber fees, pharmacy margins, and clinical support. Shopping around between providers can save £50–£100 monthly.
Can I start on 12.5mg Mounjaro, or do I have to start lower?
You must start at 2.5mg and increase every 4 weeks. Most people reach 12.5mg around week 17–20 of treatment. Starting at a lower dose reduces side effects and allows your body to adapt. Your prescriber will guide your titration schedule.
Does the NHS ever cover private Mounjaro if I'm on a waiting list?
Not routinely. NHS funding and private prescription are separate pathways. Some patients choose to pay privately while waiting for NHS assessment, then transfer to NHS prescribing if approved. Discuss this with your GP or specialist—transfer is possible if clinically appropriate.
What's included in the £180–£280 monthly private cost for Mounjaro?
The cost covers the KwikPen device (4 weeks of medication), the online clinical assessment, the prescription, and pharmacy dispensing. Some providers include follow-up support or progress tracking. Check with your chosen provider what's included before paying.
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.