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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What's the Cheapest 15mg Mounjaro in the UK?
Finding affordable Mounjaro at the maximum 15mg dose in the UK requires understanding both NHS and private prescription options. Mounjaro costs vary significantly depending on whether you access it through NHS specialist services or private online prescribing. This guide explains UK pricing, how to compare costs fairly, and how the 15mg dose of tirzepatide (Mounjaro's active ingredient) compares to Wegovy alternatives. Use our free GLP-1 weight loss calculator to estimate potential results before committing to any weight loss medication.
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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.
Mounjaro 15mg Costs vs Wegovy — What the Clinical Trials Show
Mounjaro 15mg is the maximum licensed dose in the UK and typically costs between £280–£320 per month through private prescribing services. NHS access to Mounjaro 15mg exists but is limited to specialist tier 3/4 weight management services, with significant waiting times and regional variation. Wegovy, by contrast, costs roughly £240–£300 monthly at its maximum 2.4mg dose through private providers.
Clinical trial data shows why costs matter less than results: the SURMOUNT-1 trial demonstrated Mounjaro 15mg achieved average weight loss of 20.9% body weight over 72 weeks, whilst Wegovy (semaglutide) showed approximately clinically studied weight loss in the STEP-1 trial. However, individual results vary significantly—some patients see excellent results on lower Mounjaro doses (10mg or 7.5mg), which cost less but may be equally effective for their needs.
- Mounjaro 15mg: £280–£320/month (private)
- Wegovy 2.4mg: £240–£300/month (private)
- Both require prescription and clinical assessment
- NHS access available but limited and varies by region
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.
How to Find the Cheapest Option — and Why Price Isn't Everything
The "cheapest" option depends on three factors: dose required for your results, NHS vs private access, and whether you need the maximum dose. Many patients achieve significant weight loss on Mounjaro 7.5mg or 10mg (costing £200–£250/month privately), meaning the jump to 15mg adds cost without proportional benefit for that individual.
If you qualify for NHS access through your ICB (Integrated Care Board) specialist weight management service, Mounjaro or Wegovy are typically provided free—but waiting lists are often 6–18 months. For private prescribing, compare prices across GPhC-registered pharmacies, but verify they conduct genuine clinical assessments. Use our BMI calculator and weight loss projection tool to understand your starting point and discuss realistic dose progression with your prescriber—this ensures you're not paying for a higher dose than you actually need.
- 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 Mounjaro 15mg always the best dose for weight loss?
No. Clinical evidence shows Mounjaro 10mg achieves substantial results (19.5% average weight loss), whilst 15mg adds approximately 1.4% additional loss. Your prescriber will titrate your dose gradually—many patients see optimal results on 7.5mg or 10mg and don't need to escalate to 15mg. This means lower cost without sacrificing effectiveness.
Can I get Mounjaro 15mg on the NHS in the UK?
Yes, but with significant limitations. NHS access is through specialist tier 3/4 weight management services following GP referral. Availability varies by region, and waiting lists are often very long (6–18 months in many areas). Private prescribing offers faster access but costs £280–£320/month at 15mg.
Why is Mounjaro sometimes more expensive than Wegovy if both are injections?
Mounjaro (tirzepatide) is a dual GIP+GLP-1 receptor agonist, whilst Wegovy (semaglutide) is GLP-1 only. Manufacturing costs differ, as do clinical trial investments. Both are prescription-only, and pricing varies by pharmacy and dose—comparison shopping across GPhC-registered providers often reveals better deals.
What's the difference between Mounjaro 15mg and Wegovy 2.4mg in terms of weight loss?
Mounjaro 15mg showed 20.9% average weight loss in SURMOUNT trials versus Wegovy's 14.9% in STEP trials—but these are different patient populations at different timepoints. Individual results vary widely. Your GP or prescriber will help determine which suits your health profile and budget.
Should I wait for NHS access to save money on Mounjaro 15mg?
This depends on your circumstances. NHS access is free but waiting times are long (months to years in many regions). Private prescribing costs roughly £3,360–£3,840 annually at 15mg. Discuss with your GP whether waiting is feasible or if private access allows you to start sooner with better health outcomes overall.
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.