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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Mounjaro vs Wegovy — Cost and UK Access Guide
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight management injections available in the UK, but they differ significantly in cost, access routes, and how they work. Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1 agonist only. Whether one is "better" depends on your eligibility, budget, and individual health needs. This guide compares both options across UK NHS and private access routes, so you can understand what's available to you.
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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 vs Wegovy — Private Cost and Prescription Availability
Mounjaro private cost: Typically ranges from £129 to £320 per month depending on dose, as prescribed through GPhC-registered private pharmacies following an online clinical assessment. Standard doses (5 mg to 15 mg) are available through the dose titration schedule.
Wegovy private cost: Generally ranges from £130 to £300 per month for full dose (2.4 mg), also following a dose titration process from 0.25 mg upwards. Both medications are available without NHS referral through private online prescribing services.
- Mounjaro: 4-week supply (one KwikPen with 4 doses)
- Wegovy: 4-week supply (4 pre-filled auto-injection pens)
- Both require prescription from a UK-licensed prescriber
- Both require a clinical assessment before dispensing
- Prices vary by pharmacy and dose level
- Private access is typically faster than NHS, with minimal waiting times
Use our free GLP-1 weight loss calculator to explore potential outcomes with either medication at different doses, alongside your cost considerations.
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 Access — How to Get Started
NHS route: Mounjaro and Wegovy are available through specialist tier 3 weight management services. Your GP can refer you, but NHS access is significantly limited by regional availability and waiting lists—some areas have waits of 6–12+ months. NICE has approved both tirzepatide and semaglutide for NHS use.
Private route: Faster access. You complete an online consultation with a UK-licensed prescriber, answer health screening questions, and receive a prescription if appropriate. Prescription is dispensed by a GPhC-registered pharmacy and posted to you. The entire process typically takes 1–3 business days.
- Private prescriptions do not require NHS referral
- Prescriber assesses your BMI, medical history, and weight-related conditions
- Prescription valid for 6 months in the UK
- You can switch between providers or private/NHS routes
Track your progress once started using our free progress tracker, whether you choose NHS or private access.
- 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.
Which is cheaper, Mounjaro or Wegovy in the UK?
Private costs are comparable—typically £130–£320/month depending on dose. Mounjaro starts at 2.5 mg and reaches 15 mg maximum; Wegovy starts at 0.25 mg and reaches 2.4 mg. Month-to-month costs are similar, though Mounjaro's higher maximum dose may allow faster dose titration in some cases. NHS access is free but extremely limited.
How long does it take to get Wegovy on the NHS in the UK?
NHS waiting times vary dramatically by region (ICB). Some areas have waits of 2–6 months, others 12+ months or longer. Your GP refers you to your local tier 3 specialist weight management service, which then conducts an assessment. Private access is much faster—typically 1–3 business days.
Can I get Mounjaro or Wegovy online in the UK without seeing my GP?
Yes, through private online prescribing services. You complete an online consultation with a UK-licensed prescriber, answer health questions, and receive a prescription if appropriate. This is entirely separate from NHS referral. However, you should inform your GP that you're starting a weight management injection.
Is Mounjaro better than Wegovy for weight loss?
Clinical trials showed Mounjaro (dual GIP/GLP-1) may produce slightly higher average weight loss (~20% body weight) than Wegovy (~15% body weight), but individual results vary significantly. "Better" depends on your eligibility, cost tolerance, side effect profile, and prescriber assessment. Both are prescription-only and require clinical suitability.
What happens after I get a prescription for Mounjaro or Wegovy?
You'll receive your medication by post, usually within 2–5 business days. Both start at a low dose and titrate upward every 4 weeks. You inject once weekly at home (abdomen, thigh, or upper arm). You'll typically have follow-up check-ins with your prescriber at 4–8 week intervals to monitor progress and adjust dose.
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.