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 Mounjaro 2.5mg cost in the UK?
Mounjaro 2.5mg is the starting dose for weight management in the UK, but pricing depends entirely on whether you access it through the NHS or privately. The 2.5mg dose is typically used for the first 4 weeks as part of the dose titration schedule, then increased to 5mg. This guide explains UK pricing options, NHS eligibility through specialist tier 3 services, and what to expect when starting tirzepatide treatment.
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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.
NHS vs private pricing for Mounjaro in the UK
NHS access: If prescribed through an NHS specialist weight management service (tier 3), Mounjaro is provided free at the point of care — you only pay standard prescription charges (currently £9.90 per item in England, or free if eligible). However, NHS access is limited and involves waiting lists that can span many months in some regions. NICE has approved tirzepatide for NHS use, but availability depends on your local integrated care board (ICB) commissioning decisions.
Private pricing: Through private online prescribing services, Mounjaro 2.5mg typically costs between £140–£180 per KwikPen (four-week supply). Prices vary by provider and may include consultation fees. Private access is faster — often within days — but requires paying the full cost upfront. Each KwikPen contains four pre-filled doses (one per week), so the 2.5mg dose represents a four-week supply.
- NHS route: Free (or £9.90 prescription charge) but long waiting lists
- Private route: £140–£180 per month, no waiting lists
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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.
What happens after the 2.5mg starting dose?
The 2.5mg dose is held for exactly four weeks, then typically escalated to 5mg for weeks 5–8 (minimum four weeks per dose). Each subsequent dose requires another KwikPen, with costs scaling by dose level. At 5mg, private pricing typically rises to £160–£200; at 10mg and above, costs may reach £200–£250 per month depending on your provider. Use our GLP-1 weight loss calculator to project potential outcomes at different doses, and use our BMI calculator to establish your starting point. Your prescriber will assess whether you need to progress beyond 5mg based on your response and tolerability.
- 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.
Why is 2.5mg so cheap compared to higher doses?
The 2.5mg dose is the lowest starting strength and is rarely continued long-term — it's held for only four weeks before escalation. Higher doses require more active drug per KwikPen, which increases manufacturing and supply costs. Pricing typically increases incrementally at 5mg, 7.5mg, 10mg, and above.
Can I get Mounjaro on the NHS at 2.5mg?
Yes, if referred to a tier 3 NHS specialist weight management service and approved. You'll pay only the standard prescription charge (£9.90 in England, or free if exempt). However, NHS waiting lists are lengthy in many regions — expect 3–12 months wait depending on your area.
How long do I stay on the 2.5mg dose?
Exactly four weeks. After four weeks, your prescriber will escalate you to 5mg for another four weeks minimum, then potentially higher doses depending on your tolerance and weight loss response. The KwikPen you receive contains four 2.5mg doses (one injection per week).
Is the private price for Mounjaro 2.5mg fixed?
No. Private pricing varies significantly between UK online prescribing providers — typically £140–£180 per KwikPen for the starting dose. Some providers offer bulk discounts or subscription savings. Always confirm the total cost including consultation fees before ordering.
Can I switch from private Mounjaro to NHS halfway through treatment?
It may be possible but is not straightforward. You'd need to be assessed and referred to your local NHS tier 3 service, and they would need to accept you into their programme. Many services do not allow mid-treatment switches. Discuss this with your private prescriber and GP if you're considering it.
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.