The UK's most complete GLP-1 guide
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- 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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Mounjaro 12.5mg in the UK — Cost and Access Guide
The 12.5mg dose is an escalation step in Mounjaro's titration schedule, typically reached around week 17–20 of treatment. This guide covers what the 12.5mg dose means, how much it costs in the UK, and your options for accessing tirzepatide through NHS specialist services or private prescription routes. Whether you're considering treatment or already on a lower dose, understanding cost and access is essential for informed decision-making.
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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.
UK Cost and Access for Mounjaro 12.5mg
Mounjaro 12.5mg is the penultimate dose in the KwikPen escalation schedule, available once a week. In the UK, costs vary significantly between NHS and private routes.
Private prescription costs: A single 12.5mg KwikPen (containing 4 weekly doses) typically costs between £120–£180 through GPhC-registered online prescribing services, depending on the provider. Some pharmacies offer monthly subscriptions or multi-pack discounts. Each pen lasts approximately 4 weeks, so annual private costs can range from £1,440–£2,160 if continued at this dose.
NHS access: If prescribed through an NHS specialist tier 3 or tier 4 weight management service, Mounjaro is available at no cost at point of use, though waiting times for specialist services can extend 6–12 months or longer in many regions. Regional variation in NHS availability remains significant—some integrated care boards (ICBs) have limited or no Mounjaro supply.
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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.
NHS vs Private: Which Route Works for You?
The NHS route requires GP referral to a specialist weight management service. You'll have a multidisciplinary assessment, but face potential long waiting lists. Once approved, tirzepatide is free and monitored by the specialist team.
The private route involves an online consultation with a UK-licensed prescriber (typically via a GPhC-registered pharmacy). Approval is faster (usually within days), but you pay the full cost. You'll self-monitor and can order repeat prescriptions online. Use our GLP-1 weight loss calculator to estimate potential results at the 12.5mg dose, and track your progress with our free progress tracker throughout your treatment journey.
Online prescription process: Complete a health questionnaire, have a brief telephone or video consultation with a prescriber, and receive a prescription if approved. The medicine is then dispensed by a regulated pharmacy and delivered to your address. Total time from consultation to delivery: typically 3–7 days. Private prescribers will assess your BMI, medical history, and current medications to confirm suitability—not everyone will be approved.
- 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.
How much does a single 12.5mg Mounjaro KwikPen cost in the UK?
A single KwikPen (4 weekly doses) costs approximately £120–£180 through private UK prescribing services. Costs vary by provider. Each pen lasts 4 weeks, so expect annual costs of roughly £1,440–£2,160 if continuing at this dose. NHS prescription is free, but access typically requires referral to a specialist weight management service.
Is Mounjaro 12.5mg available on the NHS?
Yes, tirzepatide (Mounjaro) is licensed and available through NHS specialist weight management services (tier 3/4). However, access varies by region and waiting times can be 6–12 months or longer. You'll need a GP referral to a specialist service. Check your local integrated care board (ICB) website for current availability in your area.
How long does it take to reach the 12.5mg dose?
Mounjaro's dose escalation schedule typically takes 20+ weeks to reach 12.5mg. You start at 2.5mg for 4 weeks, then increase by 2.5mg every 4 weeks: 5mg, 7.5mg, 10mg, 12.5mg, with a final escalation to 15mg available after week 21. Your prescriber may adjust timing based on your tolerance and response.
What's the difference between Mounjaro and Wegovy at higher doses?
Mounjaro (tirzepatide) is a dual GIP + GLP-1 agonist with a maximum dose of 15mg weekly, while Wegovy (semaglutide) is a GLP-1 agonist only with a maximum dose of 2.4mg weekly. Clinical trial data suggests Mounjaro's dual mechanism may support slightly greater average weight loss, though individual results vary significantly. Both are prescription-only.
Can I switch between NHS and private Mounjaro prescriptions?
Technically yes, but it's not straightforward. If you start on private prescription and then gain NHS access through a specialist service, the NHS team will take over your care and monitoring. Conversely, if you're on NHS treatment and want to move to private, you'd need to pause NHS treatment and start a private prescription. Always discuss any switch with your current prescriber first.
Ready to take control of your weight loss journey?
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