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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Cheapest 15mg Mounjaro UK — What You Actually Pay
Finding the cheapest 15mg Mounjaro in the UK depends on whether you access it through the NHS or private prescription. Mounjaro (tirzepatide) is a prescription-only weight management injection available at maximum 15mg dose, and costs vary significantly between routes. This guide explains actual UK pricing, where to find it, and what affects the final cost you'll pay.
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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.
How Much Does 15mg Mounjaro Cost in the UK?
Private prescription pricing: 15mg Mounjaro through private online prescribing services typically costs between £280–£350 per month, depending on the provider and any discounts available. Each KwikPen contains four doses (four weeks' supply), so you're paying for the month upfront. Some providers offer volume discounts or subscription savings, reducing costs to approximately £240–£280 monthly if you commit to longer treatment periods.
NHS route: If prescribed through NHS specialist weight management services, there is no charge at point of use (you pay only standard NHS prescription fees of £9.90 per item in England, or nothing if you're exempt). However, NHS availability is extremely limited — most areas have waiting lists of months or years, and not all ICBs fund tirzepatide weight management yet.
The "cheapest" option depends on your circumstances: NHS is free if available locally, but private access is faster and doesn't require specialist referral.
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.
What Affects Mounjaro 15mg Pricing?
Dose progression: You won't start at 15mg — tirzepatide requires dose titration starting at 2.5mg and increasing every 4 weeks. Early doses (2.5mg, 5mg, 7.5mg) cost less per pen than the 15mg maximum. Your total monthly cost depends on which dose you're actually taking.
Provider variation: Private costs differ between GPhC-registered online pharmacies — comparing at least 2–3 providers can save £30–£50 monthly. Some offer payment plans or loyalty discounts. Use our GLP-1 weight loss calculator to estimate your potential treatment timeline and budget for the full course.
Treatment duration: Most people take Mounjaro for 6–12 months minimum. Calculate your total likely cost (dose progression + expected duration) before starting.
- 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 15mg Mounjaro available on the NHS in the UK?
Yes, but only through specialist tier 3 weight management services following GP referral. Availability varies by region (ICB), and waiting lists are long in many areas. NICE approved tirzepatide for NHS weight management in 2023, but funding and access remain patchy. Most people accessing 15mg Mounjaro quickly use private prescription routes.
What's the difference between NHS and private Mounjaro 15mg?
The medication is identical — same tirzepatide, same KwikPen device. The difference is access speed and cost. NHS is free (just prescription fees) but involves waiting. Private is faster but costs £280–£350/month. Both require a prescription from a UK-licensed prescriber and clinical assessment.
Can I switch between NHS and private Mounjaro mid-treatment?
Yes, you can switch routes, but your prescriber needs to be informed. If switching from private to NHS, request an NHS referral to specialist services. If switching from NHS to private, your NHS prescriber will need to stop treatment and a private prescriber will reassess you. Always inform both providers.
Why does 15mg Mounjaro cost more than lower doses?
You don't pay per dose with most UK private pharmacies — you pay a flat monthly rate for the KwikPen, which contains four weeks of whatever dose you're taking. Pricing is usually tiered by maximum dose strength. Starting doses (2.5mg–5mg) may be cheaper; 15mg pens cost more because they contain the maximum strength formulation.
How long will I take 15mg Mounjaro for?
That depends on your individual response and health goals. Clinical trials show results at 12–20 weeks typically. Most people take Mounjaro for 6–12 months minimum. Some continue longer. Your prescriber will review progress regularly. Use our GLP-1 weight loss calculator to project your likely treatment timeline and budget accordingly.
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.