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
Free tracker included with every download this week
Mounjaro Pens in the UK — Cost, Access & How to Get Them
Mounjaro pens (tirzepatide) are prescription-only weight management injections available in the UK through both NHS and private routes. The cost, availability, and access pathway differ significantly depending on whether you go through your GP, NHS specialist services, or a private online prescriber. Understanding your options helps you make an informed decision about which route suits your circumstances and timeline.
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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.
Private Access & Mounjaro Pen Costs in the UK
Private prescription costs for Mounjaro pens typically range from approximately £130 to £320 per month, depending on the dose prescribed. A single KwikPen device contains four weekly doses, so your monthly cost depends on which dose your prescriber recommends. Starting doses (2.5 mg) are at the lower end of the price range, whilst higher maintenance doses (15 mg) cost more. Private access is available through UK-registered online pharmacies following an online clinical assessment with a licensed prescriber — no NHS referral needed. The process is straightforward: complete a consultation form, a prescriber reviews your health details, and if suitable, your prescription is issued and dispensed directly to your home. Private access typically takes 1–2 weeks from initial consultation to delivery. This route suits those who don't qualify for NHS services, prefer shorter waiting times, or want to start treatment immediately.
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 Access vs Private Route — Which Option Is Right for You?
NHS access to Mounjaro is through specialist tier 3 or 4 weight management services, not standard GP prescription. Your GP must refer you to your local specialist service, which then assesses your eligibility and manages your treatment if suitable. NHS access is free at the point of use but availability varies significantly by region, with waiting lists often several months long. Eligibility criteria include a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Our free BMI calculator helps you check where you stand. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at lower BMI thresholds (27.5+). Compare potential weight loss outcomes using our GLP-1 weight loss calculator to understand what different doses might achieve.
- 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.
How much do Mounjaro pens cost privately in the UK?
Private Mounjaro pen costs typically range from £130 to £320 per month depending on dose. A KwikPen contains four weekly injections, so your cost depends on which dose you're prescribed. Starting doses are cheaper than maximum doses. Prices may vary slightly between online prescribers.
Can I get Mounjaro pens on the NHS in the UK?
Yes, but only through NHS specialist tier 3/4 weight management services following GP referral. NHS access is free but availability is limited and varies by region. Waiting lists can be long. Private access is faster but costs £130–£320/month depending on dose.
What's the difference between getting Mounjaro privately vs on the NHS?
NHS requires GP referral to specialist services, is free, but has long waiting lists and limited availability by region. Private requires no NHS referral, is faster (1–2 weeks), but costs £130–£320/month. Both require clinical assessment to confirm you're eligible.
How do I get a private Mounjaro prescription online?
Complete an online health assessment with a UK-licensed prescriber, provide your medical history, and declare any medications. The prescriber reviews your details and issues a prescription if suitable. Your prescription is then dispensed and posted to your home within days.
What dose of Mounjaro will I be prescribed, and how much will it cost?
Starting dose is usually 2.5 mg (cheaper), then increased gradually to maintenance (typically 5–15 mg). Your prescriber decides based on your health and response. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses and budget accordingly.
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.