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 to Use Mounjaro Pen in the UK: Cost and Access
Mounjaro (tirzepatide) comes as a pre-filled KwikPen injection device for once-weekly use. If you're considering this prescription weight management medicine, understanding how to access it in the UK and what it costs is essential. This guide covers NHS and private routes, pricing, and what to expect from the prescription process. Use our free GLP-1 weight loss calculator to explore potential outcomes at different Mounjaro doses before speaking to a prescriber.
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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 Mounjaro Access and UK Costs
Private prescription costs: Mounjaro is available through UK private prescribing services following an online clinical assessment. Costs typically range from £129 to £320 per month depending on your dose and provider—starting doses (2.5 mg) are generally less expensive than maximum doses (15 mg). Each KwikPen contains four weekly injections (one month's supply). Private access does not require NHS referral or waiting lists. The online consultation process involves completing a health questionnaire, which is reviewed by a UK-licensed prescriber. If approved, your prescription is sent to a GPhC-registered pharmacy for dispensing. Many private services offer flexible payment options including monthly subscriptions or pay-per-dose models. Costs may vary slightly between providers, so it's worth comparing options. Private access typically provides faster access than NHS routes, with treatment starting within days of approval rather than months.
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 Routes and What to Expect
NHS access: The NHS provides Mounjaro through specialist tier 3 and tier 4 weight management services following referral from your GP. NICE has approved tirzepatide for NHS use, but availability varies significantly by region (ICB area). Waiting lists for NHS specialist services can be several months to years in many areas. Your GP can advise on local availability and referral eligibility based on your BMI and health conditions. Online consultation process: Private services ask for your height, weight, current medications, and medical history. A licensed prescriber reviews your information to assess suitability—this typically takes 24–48 hours. Once approved, your Mounjaro prescription arrives at a pharmacy within 1–2 working days. You'll receive injections at your starting dose (usually 2.5 mg) with guidance on dose escalation over weeks and months.
- 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.
What's the difference between Mounjaro and Wegovy in the UK?
Both are prescription-only weight management injections available in the UK. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro typically costs £129–£320 monthly; Wegovy costs vary similarly. Clinical trials showed Mounjaro resulted in slightly higher average weight loss (~21% body weight) compared to Wegovy (~15%), though individual results vary significantly.
Can I get Mounjaro on the NHS in the UK?
Yes, NICE has approved tirzepatide (Mounjaro) for NHS use through specialist weight management services. However, access is limited and varies by region. You'll need referral from your GP to a tier 3 or tier 4 specialist service. Waiting lists can be very long in many areas. Private prescription is an alternative route if NHS access isn't available locally.
How much does a Mounjaro KwikPen cost privately in the UK?
Private Mounjaro costs typically range from £129 to £320 per month, depending on your dose. Starting doses (2.5 mg) are cheaper than maximum doses (15 mg). Each pen contains four weekly injections. Many private prescribing services offer monthly subscriptions or pay-per-dose options. Costs may vary between providers—compare services for best pricing.
What happens during an online consultation for Mounjaro?
You'll complete a health questionnaire covering your weight, height, medications, and medical history. A UK-licensed prescriber reviews your information within 24–48 hours to assess suitability for Mounjaro. If approved, your prescription is sent to a GPhC-registered pharmacy for dispensing. You'll receive guidance on how to use your Mounjaro KwikPen and dose escalation schedules.
Is Mounjaro dose titration more expensive on private prescription?
No. Private Mounjaro costs cover the full titration schedule—you pay the set monthly fee regardless of whether you're on 2.5 mg, 5 mg, 10 mg, or 15 mg. Some providers offer lower starting costs for the initial 2.5 mg dose, then higher costs as you escalate. Always clarify pricing with your provider before starting treatment. Check your BMI using our free BMI calculator to understand your eligibility before consulting a prescriber.
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.