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 starter dose of tirzepatide and is the first step in a gradual dose titration schedule. The cost varies significantly depending on whether you access it through the NHS or privately. NHS access is available through specialist tier 3 weight management services, though availability varies by region. Private prescriptions through UK-licensed online pharmacies typically range from £129 to £180 per KwikPen (which contains 4 weeks' supply of the 2.5mg dose), though prices fluctuate. This guide explains UK pricing, what affects the cost, and your access options.
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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.
Mounjaro 2.5mg Pricing in the UK
Private prescriptions: The 2.5mg starter dose typically costs between £129–£180 per KwikPen through GPhC-registered online pharmacies. A KwikPen contains four pre-filled pens, providing a month's supply (one injection per week). Prices vary between providers and may change based on demand and supply. Some private pharmacies offer discounted rates for bulk prescriptions or repeat customers.
NHS access: When prescribed through an NHS specialist weight management service, Mounjaro may be available at no cost at the point of use (covered by your local Integrated Care Board). However, NHS access is limited and highly variable by region. Many areas have waiting lists of several months to over a year. Your GP can refer you to your local tier 3 service, but eligibility assessment is required.
Additional costs: Private prescriptions require an online consultation with a UK-licensed prescriber (typically £20–£50), plus the medication cost. This is separate from the pharmacy fee.
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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 Affects Mounjaro 2.5mg Cost?
Several factors influence the price you pay: supplier stock and demand affect wholesale costs, which are reflected in retail pricing; competition between online pharmacies drives price variation (checking multiple providers is worthwhile); prescription type (first prescription vs repeat prescription) may have different pricing; bulk purchasing of multiple months at once sometimes attracts discounts; and regional NHS availability determines whether you access it free or privately. The 2.5mg dose is typically the most affordable per-pen, as it's the starting dose with lower manufacturing complexity than higher strengths.
- 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 Mounjaro 2.5mg more affordable than higher doses?
The 2.5mg dose contains the lowest concentration of tirzepatide. Manufacturing, packaging, and distribution costs are proportionally lower than 5mg, 10mg, or 15mg doses. This is why the starter dose is often the most competitively priced option. As you progress through dose titration, per-pen costs typically increase slightly.
Can I access Mounjaro 2.5mg free on the NHS?
Yes, if prescribed through a specialist NHS tier 3 weight management service in your area. However, NHS access varies significantly by region, and waiting lists are lengthy in many areas. Your GP can refer you, but eligibility assessment is required (usually BMI 30+, or BMI 27+ with weight-related health conditions). Check with your local Integrated Care Board for availability.
How long does one Mounjaro 2.5mg KwikPen last?
Each KwikPen contains four pre-filled pens, providing one month's supply (one injection per week). You stay on the 2.5mg dose for at least four weeks before your prescriber considers increasing to 5mg, so one KwikPen covers the entire starter phase for most people.
Is Mounjaro 2.5mg the same as tirzepatide?
Yes. Mounjaro is the brand name for tirzepatide. The 2.5mg dose is the starter strength. Tirzepatide is a dual GIP and GLP-1 receptor agonist, which is why it has a dual mechanism of action compared to single GLP-1 medications like Wegovy (semaglutide). Always check your prescription carefully to confirm the dose and frequency.
How does Mounjaro 2.5mg pricing compare to Wegovy?
Wegovy (semaglutide) starter doses are typically similar in price (£120–£170 per pen), though Wegovy pens contain one injection each (weekly), whereas Mounjaro KwikPens contain four weeks' supply. Per-week cost is comparable. Our GLP-1 weight loss calculator can help you compare projected outcomes between the two medications. Ultimately, which is suitable depends on individual clinical assessment and prescriber recommendation.
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.