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 KwikPen 2.5mg — Cost and Access in the UK
Mounjaro (tirzepatide) is available in the UK as a once-weekly injection in the KwikPen device, with 2.5mg being the standard starting dose. The cost and how you access this prescription-only medicine varies significantly depending on whether you go through NHS specialist services or use private online prescription routes. Understanding your options, eligibility, and realistic costs helps you make an informed decision about this weight management treatment. Our free GLP-1 weight loss calculator can help you explore potential outcomes if you're considering this medication.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 KwikPen 2.5mg Private Prescription Costs in the UK
Private prescription costs for Mounjaro 2.5mg typically range from £129 to £199 per month, depending on your provider and whether you're starting treatment or already established on a dose. Each KwikPen contains four weekly injections (a four-week supply), so a single pen at 2.5mg usually costs £32–£50 per week. At the 2.5mg starting dose, you'll stay for the first four weeks before your prescriber reviews whether to increase to the next dose. Private access is through a clinical online consultation with a UK-licensed prescriber, followed by dispensing via a GPhC-registered pharmacy — no NHS referral needed. Costs may be lower if you commit to longer treatment periods or use certain providers' pricing structures. Keep in mind that costs increase as your dose increases — the maximum dose (15mg) typically costs £180–£280 monthly, and most people eventually escalate beyond the 2.5mg starting point. Always confirm the exact cost and frequency before committing.
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 — Route Comparison
NHS access is through a tier 3 specialist weight management service following a GP referral, and the medication is free on prescription — however, waiting times vary dramatically by region, with some areas having delays of 6–18 months. Private access is faster (consultation and prescription within days) but you pay the full cost yourself. Private prescriptions are issued by UK-licensed prescribers after an online assessment confirming your eligibility (BMI ≥30, or BMI 27–29.9 with weight-related health conditions). You'll need to answer health questions, provide your medical history, and confirm you're not pregnant or taking incompatible medications. Choose private if you want to start immediately; choose NHS if you're willing to wait and want the medication free. Both routes provide legitimate, safe access to tirzepatide.
- 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 Mounjaro KwikPen 2.5mg available on the NHS in the UK?
Yes, tirzepatide (Mounjaro) is approved by NICE and available on the NHS for eligible adults. Access is through specialist tier 3 weight management services via your GP — you cannot get it from standard GP prescription. Waiting lists are often long, but the medication is free once approved and prescribed.
What does a private Mounjaro KwikPen prescription cost per month?
Private prescription costs typically range from £129–£199 per month for the 2.5mg starting dose. Costs increase as your dose escalates — by maximum dose (15mg), expect £180–£280 monthly. Each pen lasts four weeks. Always check current pricing with your chosen provider before starting.
How long do I stay on the 2.5mg starting dose?
You remain on 2.5mg for four weeks (one KwikPen). After this, your prescriber reviews your progress and tolerability, then typically escalates you to 5mg for the next four weeks. Dose increases continue every four weeks until you reach an effective maintenance dose or your prescriber decides to hold at a particular dose.
Can I switch from NHS to private Mounjaro treatment mid-course?
Yes, you can switch from NHS to private (or vice versa) — you'll simply have a new prescription issued by your new provider. Inform both your NHS service and your private prescriber to avoid accidental overlaps. The transition is straightforward and often happens when NHS waiting times are lengthy.
What information do I need to provide for a private Mounjaro consultation?
You'll need your current weight and height (to calculate BMI), medical history, current medications, allergies, pregnancy status, and confirmation of any weight-related health conditions (diabetes, high blood pressure, sleep apnoea). The online assessment takes 10–15 minutes. Our free BMI calculator can help you confirm your BMI before the consultation.
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.