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
What Does 15mg Mounjaro Cost in the UK?
15mg is the maximum dose of Mounjaro (tirzepatide) available in the UK, and costs vary significantly depending on whether you access it through the NHS or privately. Most people never reach the 15mg dose immediately — you typically start at 2.5mg and increase every 4 weeks, with many finding results at lower doses like 5mg or 10mg. Understanding both NHS and private pricing helps you make an informed decision about which route suits your situation.
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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.
NHS Access and Cost for 15mg Mounjaro
On the NHS, Mounjaro is free at the point of use if you meet eligibility criteria and are prescribed through a tier 3 specialist weight management service. However, accessing it through the NHS is complex. You must first be referred by your GP to your local Integrated Care Board (ICB) weight management service, and availability varies dramatically across the UK. Some regions have long waiting lists of 6–12 months or longer, whilst others have limited availability.
NICE guidance approves tirzepatide for NHS use in adults with:
- BMI of 30 kg/m² or above, or
- BMI of 27–29.9 kg/m² with weight-related comorbidities (type 2 diabetes, hypertension, cardiovascular disease, or sleep apnoea)
- Lower thresholds for South Asian, Chinese, Black African, and Black Caribbean adults
The SURMOUNT clinical trial showed that participants on 15mg Mounjaro lost an average of 20.9% of their body weight over 72 weeks alongside diet and activity changes — though individual results vary significantly.
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.
Private Cost and Access for 15mg Mounjaro
Privately, 15mg Mounjaro typically costs between £280–£320 per month through UK-registered online pharmacies following an online clinical assessment. This includes the prescription, clinical consultation fee, and the KwikPen delivery. You do not need an NHS referral — a licensed UK prescriber will assess your eligibility and issue a prescription if appropriate.
Private access is faster (typically 7–14 days from consultation to delivery) and does not depend on regional NHS availability. However, you pay out-of-pocket. Compare this with lower doses: 5mg costs approximately £130–£160/month, and 10mg costs around £200–£240/month. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses, then discuss cost and suitability with a prescriber.
- 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 15mg Mounjaro cost on the NHS?
If prescribed through NHS tier 3 specialist services, Mounjaro is free at point of use. However, accessing NHS services can involve long waiting lists and regional variation. You must be referred by your GP and meet NICE eligibility criteria (BMI ≥30, or ≥27 with weight-related health conditions).
What's the private cost of 15mg Mounjaro in the UK?
Private 15mg Mounjaro typically costs £280–£320 per month through registered UK pharmacies. This includes the KwikPen, prescription, and online clinical assessment. Costs vary slightly by provider. Access is faster than NHS (7–14 days) and doesn't require GP referral.
Is 15mg always the dose I'll need?
No. Most people start at 2.5mg and increase every 4 weeks. Many achieve good results at 5mg or 10mg. Reaching 15mg takes around 20–24 weeks of gradual titration. Your prescriber will assess the right dose for you.
How does 15mg Mounjaro cost compare to Wegovy?
Both Mounjaro and Wegovy cost similarly — around £280–£320/month at their maximum doses. The SURMOUNT trial showed 15mg Mounjaro produced slightly higher average weight loss (20.9%) than Wegovy's maximum (14.9%), though individual results vary. Cost comparison should also include prescriber fees and regional variation.
Can I switch from NHS to private Mounjaro if waiting lists are too long?
Yes. If your NHS waiting list is very long, you can pursue private access independently. However, inform your GP of your decision. If you later want to return to NHS services, there may be administrative steps required. Always discuss options with your GP or a licensed prescriber first.
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.