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 15mg in the UK — How to Access & What You Need to Know
Mounjaro 15mg is the highest maintenance dose of tirzepatide available in the UK for weight management. This is typically reached after a 20-week dose escalation from the starting 2.5mg injection, though not all patients progress to the maximum dose. Understanding how Mounjaro 15mg fits within NHS and private prescribing in the UK, and whether this dose is right for you, requires input from your GP or prescriber. This guide explains NHS NICE approval, eligibility criteria, and your prescribing options in the UK.
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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 Approval, Eligibility, and UK Prescribing Pathways
NICE Approval: NICE has approved tirzepatide (Mounjaro) for use within NHS specialist weight management services in England, Wales, and Northern Ireland. Approval applies to adults who meet NHS eligibility criteria and have been assessed by a tier 3 or tier 4 specialist weight management service.
NHS Eligibility for Mounjaro (Any Dose): You may be eligible for NHS Mounjaro if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with at least one weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at a BMI of 27.5 or above due to higher health risk at lower weights.
- Access is through NHS tier 3 specialist weight management services — not routine GP prescription
- Regional variation: availability depends on your Integrated Care Board (ICB) and local service capacity
- Waiting times can be lengthy in many areas — sometimes 6–12+ months
- Not available through standard GP prescribing for routine weight management
Calculate your BMI using our free BMI calculator above to check where you fall against NHS thresholds.
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 vs Private Routes — Accessing Mounjaro 15mg
NHS Route: Requires GP referral to specialist tier 3 services, specialist assessment, and prescription. Free at the point of use but subject to local ICB approval and waiting lists.
Private Route: Available through GPhC-registered online prescribing services. A UK-licensed prescriber assesses your eligibility following an online consultation and issues a prescription if appropriate. Faster access (typically within days) but costs apply — around £250–£320 per month depending on your dose and provider. This route does not require NHS referral.
Whichever route you choose: You will only reach the 15mg dose if lower doses (2.5mg through 12.5mg) are tolerated and effective. Dose progression is individual — many patients stabilise at lower doses. A prescriber will assess whether escalation to 15mg is appropriate for your health and response to treatment.
- 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.
What is Mounjaro 15mg?
Mounjaro 15mg is the maximum once-weekly dose of tirzepatide available in the UK. It is a dual GIP and GLP-1 receptor agonist prescribed for weight management in adults meeting NHS or private prescribing criteria. Clinical trials showed average weight loss of around 21% body weight, though individual results vary significantly.
Who can get Mounjaro 15mg on the NHS in the UK?
You must meet NHS eligibility (BMI ≥30 or BMI 27–29.9 with weight-related health conditions) and be assessed by a specialist tier 3 weight management service. Regional availability varies significantly by ICB. Your GP can refer you, but approval depends on local service capacity and criteria.
How long does it take to reach the 15mg dose?
The standard titration schedule takes approximately 20 weeks to progress from 2.5mg to 15mg, with dose increases every 4 weeks (2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg). However, not all patients progress this far — your prescriber will assess tolerability and effectiveness at each stage.
Can I get Mounjaro 15mg privately in the UK?
Yes. Private online prescribing services can issue Mounjaro prescriptions following an online clinical assessment. This bypasses NHS waiting lists but incurs monthly costs (typically £250–£320). The prescription is dispensed by a GPhC-registered pharmacy.
What happens if I cannot tolerate the 15mg dose?
Not reaching 15mg is normal. Many patients stabilise at lower effective doses (5mg, 10mg, or 12.5mg). Your prescriber will not escalate if side effects outweigh benefits. Use our GLP-1 weight loss calculator to explore projected outcomes at different doses and discuss the best dose for you with your prescriber.
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.