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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GLP-1 vs Mounjaro — Cost and Access in the UK
If you're considering weight loss medication in the UK, understanding how to access GLP-1 injections like Wegovy versus tirzepatide (Mounjaro) — and what they cost — is essential. Both are prescription-only medications available through NHS specialist services or private online prescribing, but access routes and costs differ significantly. This guide explains how to get either medication, what to expect from a clinical assessment, and realistic costs for UK patients seeking weight management support.
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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.
UK Private Prescription Costs for GLP-1 and Mounjaro
Private prescription costs vary depending on the medication, dose, and prescribing service. For Wegovy (semaglutide), private prescriptions typically cost between £129–£280 per month at standard doses, with starting doses (0.25–0.5 mg) at the lower end and maintenance doses (1.7–2.4 mg) higher. For Mounjaro (tirzepatide), private costs generally range from £150–£320 per month, with dose titration affecting price — starting doses (2.5 mg) cost less than maximum doses (15 mg).
- Each dose is a four-week supply (four pens per KwikPen package)
- Prices vary between GPhC-registered online pharmacies — shopping around is worthwhile
- Some services bundle prescribing fees (typically £40–£100) into monthly costs; others charge separately
- Most UK private providers offer monthly subscriptions, reducing per-dose costs over time
- No NHS prescription charge applies — you pay the full cost privately
Neither medication is available on NHS prescription outside of specialist tier 3 and tier 4 weight management services, and NHS availability varies dramatically by region.
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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 — How to Get Started
NHS route: Your GP can refer you to a specialist weight management service (tier 3), where tirzepatide may be prescribed if you meet eligibility criteria (BMI ≥30, or ≥27 with comorbidities). NHS access is free, but waiting times can be months or years depending on your region, and availability varies significantly by ICB.
Private route: You can access both Wegovy and Mounjaro through GPhC-registered online prescribing services without NHS referral. An online clinical assessment with a UK-licensed prescriber takes 15–30 minutes, covering medical history, current medications, and eligibility. If approved, your prescription is dispensed by an affiliated pharmacy and delivered to your home. Most services offer ongoing prescriber support and dose adjustments as you progress through titration.
Try our free GLP-1 weight loss calculator to explore potential outcomes at different doses, and use our BMI calculator to confirm your eligibility category.
- 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 the difference between Wegovy and Mounjaro in terms of cost?
Wegovy (semaglutide) typically costs £129–£280/month privately; Mounjaro (tirzepatide) ranges £150–£320/month. Costs depend on dose — lower starting doses cost less. Both require ongoing monthly costs unless prescribed through NHS specialist services, which are free but have limited regional availability and long waiting lists.
Can I get Mounjaro on the NHS in the UK?
Mounjaro may be prescribed through NHS specialist tier 3 weight management services if you meet eligibility criteria (BMI ≥30 or ≥27 with comorbidities). NHS access is free, but availability varies significantly by region. Ask your GP about referral to your local specialist service — waiting times can be substantial.
How does the private online prescription process work?
You complete a brief online health questionnaire and have a consultation (15–30 minutes) with a UK-licensed prescriber via video or phone. If approved, your prescription is sent to an affiliated GPhC-registered pharmacy and delivered to your home. Most services offer follow-up support for dose adjustments and ongoing monitoring.
Are there hidden costs with private GLP-1 or Mounjaro prescriptions?
Some services bundle prescribing fees (£40–£100) into the monthly cost; others charge separately. Check whether initial consultations, follow-up reviews, or dose changes incur additional fees. Delivery is usually included. Monthly costs are straightforward once you know your dose and service provider.
What's the cheapest way to get Mounjaro or Wegovy in the UK?
NHS prescription is free if you can access specialist services — waiting lists are the barrier. Privately, costs are similar across providers at the same dose, so compare services for prescribing fees, delivery costs, and ongoing support rather than medication price. Buying multiple months ahead sometimes offers discounts.
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.