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 15mg Mounjaro Cost in the UK?
The 15mg dose is the maximum strength of Mounjaro (tirzepatide) available in the UK, typically reached after several weeks of dose titration. If you're considering this medication for weight management, understanding the costs and how to access it is essential. Mounjaro is a prescription-only medicine requiring clinical assessment before dispensing, and the cost varies significantly depending on whether you access it through the NHS or privately.
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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.
Private Prescription Costs for 15mg Mounjaro in the UK
The private cost of 15mg Mounjaro in the UK typically ranges from £250 to £350 per month, though this varies by provider and whether you purchase individual pens or subscription packages. Each KwikPen contains a single 15mg dose for one week, so a monthly supply requires four pens. Some private prescribing services offer discounts for longer-term commitments or subscription models, which can reduce the per-dose cost. The final price depends on the prescribing service's clinical fees, pharmacy dispensing fees, and any consultation charges. Unlike branded medications in pharmacies, private tirzepatide prescribing operates through online consultations with UK-licensed prescribers, so costs are set by the service provider rather than a standard retail price. If you're comparing costs, it's worth calculating the total monthly commitment rather than per-pen prices, as bundled packages are often more economical.
- Monthly supply (4 pens × 15mg): approximately £250–£350
- Prescription and clinical assessment fees: typically £20–£50
- Subscription or bulk discounts may reduce the overall cost
- Storage and delivery fees may apply depending on provider
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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 Access: Routes to Getting 15mg Mounjaro
NHS access: Mounjaro is approved by NICE for use within NHS specialist weight management services (tier 3 and tier 4), but it is not available through standard GP prescription. You must be referred to a specialist weight management service, typically by your GP, and assessed for clinical suitability. NHS availability varies significantly by region and waiting lists can extend many months. Private access: You can obtain a Mounjaro prescription without NHS referral through a UK-licensed prescriber via online consultation. This route is faster — assessments can be completed within days — but requires private payment. The online consultation process involves completing a health questionnaire, sometimes a video call with a prescriber, and if suitable, a prescription is issued to a GPhC-registered pharmacy. Both routes require a clinical assessment; neither is available without one.
- 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's included in the monthly cost of 15mg Mounjaro?
The monthly cost typically covers four pre-filled KwikPens (one per week), though some providers bundle clinical assessment and prescription fees separately. Always check whether the quoted price includes the prescriber consultation fee, pharmacy dispensing fee, and delivery. Storage guidance and patient support may also be included. Comparison shop to understand the total monthly commitment before committing.
Is 15mg Mounjaro cheaper on the NHS?
Yes, if you can access it through the NHS, there is no medication cost — you pay only standard prescription charges (currently £10.65 per prescription in England, or nothing if exempt). However, NHS access requires specialist referral and can involve very long waiting lists. Many people access it privately due to speed of access, even though there is a cost.
Can I start at 15mg Mounjaro or do I need to titrate from a lower dose?
You cannot start at 15mg. Mounjaro requires dose titration: you begin at 2.5mg and increase every 4 weeks (2.5 → 5 → 7.5 → 10 → 12.5 → 15mg). This means reaching maximum dose takes approximately 20 weeks. Starting at a lower dose reduces side effects and allows your body to adjust. Our GLP-1 weight loss calculator can help you estimate your progression timeline and potential outcomes at different doses.
How does 15mg Mounjaro compare to Wegovy in terms of cost?
Mounjaro 15mg (tirzepatide) and Wegovy 2.4mg (semaglutide) have similar UK private costs, typically £250–£350 monthly. Mounjaro is a dual GIP/GLP-1 agonist while Wegovy is a GLP-1 agonist only; clinical trial data suggest Mounjaro may have slightly larger average weight loss, but individual results vary. Your prescriber can advise which is more suitable based on your health profile.
What happens if I can't afford the ongoing cost of 15mg Mounjaro?
If private costs are unaffordable, discuss NHS access with your GP — you may be eligible for referral to a specialist weight management service, though waiting lists vary. Some people reduce frequency or pause treatment temporarily. Speak honestly with your prescriber or GP about financial concerns; there may be support options available, and your healthcare provider can advise on alternatives or payment plans in some cases.
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.