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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Cheapest 2.5mg Mounjaro vs Wegovy in the UK
If you're looking for the cheapest 2.5mg Mounjaro option in the UK, it's worth understanding how it compares to Wegovy before committing to either medication. Both are prescription-only weight management injections, but they work differently, cost differently, and may suit different people. This guide compares the starting doses, mechanisms, clinical trial data, and UK pricing so you can make an informed decision with your prescriber.
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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.
How 2.5mg Mounjaro and Wegovy Compare — Mechanism and Trial Data
Mounjaro (tirzepatide) at 2.5mg is a dual GIP and GLP-1 receptor agonist — meaning it activates two hormone pathways simultaneously. In clinical trials (SURMOUNT-1), the starting 2.5mg dose showed measurable appetite reduction and early weight loss effects. Wegovy (semaglutide) begins at 0.25mg, a much lower starting dose, and works via GLP-1 alone. In the STEP-1 trial, Wegovy showed an average weight loss of around 14.9% body weight at the maximum dose (2.4mg) over 68 weeks alongside diet and exercise.
- Mounjaro 2.5mg: Dual mechanism (GIP + GLP-1), starting dose for 4 weeks
- Wegovy 0.25mg: Single mechanism (GLP-1 only), lowest starting dose for 4 weeks
- Both are once-weekly KwikPen injections
- Individual results vary significantly — clinical trial averages do not predict personal outcomes
- Both require a UK prescription following clinical assessment
The "cheapest" option depends on your private provider — prices vary £129–£320/month depending on dose and pharmacy. NHS access is through specialist tier 3 services but involves waiting lists. Try our GLP-1 weight loss calculator to compare projected outcomes at different doses for both medications.
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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
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Getting the Cheapest 2.5mg Mounjaro — NHS vs Private, and Which Suits You
Through the NHS, Mounjaro at 2.5mg is free if prescribed by a specialist weight management service — but NHS access is limited and waiting lists are long (often months to years depending on your region). Through private online prescription with a UK-licensed prescriber, 2.5mg Mounjaro costs approximately £129–£180 per month (one KwikPen = 4 weekly doses). Price varies between GPhC-registered pharmacies.
Whether 2.5mg Mounjaro or Wegovy suits you depends on individual factors: your BMI, existing health conditions, medication tolerance, and prescriber assessment. Both require a clinical evaluation before prescription. Your GP or prescriber will assess tirzepatide eligibility UK criteria based on your health profile, not price alone. Use our BMI calculator to check your starting point, then discuss options with your prescriber.
- 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 2.5mg Mounjaro cheaper than Wegovy in the UK?
Privately, both medications cost approximately £129–£320/month depending on dose and provider — 2.5mg Mounjaro and 0.25mg Wegovy are comparable in price. Through the NHS, both are free if prescribed by specialist services, but access is limited. The cheapest private option requires comparing pharmacies' current pricing.
What's the difference between Mounjaro and Wegovy at starting doses?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is GLP-1 only. Mounjaro's 2.5mg starting dose is higher than Wegovy's 0.25mg. In clinical trials, the dual mechanism showed slightly higher average weight loss — but individual results vary significantly.
Can I get 2.5mg Mounjaro through the NHS?
Yes, through NHS specialist weight management services (tier 3), but only after referral from your GP. Waiting lists are long in many regions. Private online prescription with a UK-licensed prescriber is faster — typically 1–2 weeks from consultation to delivery.
Will 2.5mg Mounjaro dose start me on my way to maximum strength?
Yes. 2.5mg is the starting dose for all Mounjaro users. You stay on this for 4 weeks, then your prescriber increases it gradually (5mg, 7.5mg, 10mg, 12.5mg, 15mg max) based on tolerance and response. Maximum dose is 15mg weekly.
Which is cheapest long-term — Mounjaro or Wegovy?
Long-term cost depends on which dose you need. Wegovy's maximum is 2.4mg; Mounjaro's is 15mg. At equivalent efficacy doses, private pricing is similar (£180–£250/month). Your prescriber determines which suits you — not cost. Using our GLP-1 weight loss calculator can help estimate potential needs.
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.