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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Mounjaro Pens: NHS Prescribing in the UK
Mounjaro pens (tirzepatide) are prescription-only weight management injections available through the NHS and private prescribing in the UK. Each KwikPen is a pre-filled auto-injector containing four weekly doses of this GLP-1 and GIP receptor agonist medication. Access through the NHS requires referral to a tier 3 specialist weight management service, though waiting times vary significantly by region. This guide explains how to access Mounjaro pens, eligibility criteria, and what to expect from NHS treatment pathways.
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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.
NHS Eligibility and Prescribing Pathway for Mounjaro Pens
NICE approval: Tirzepatide (Mounjaro) is approved by NICE for use within NHS specialist weight management services for eligible adults. You cannot obtain Mounjaro through a standard GP prescription—it must come through tier 3 or tier 4 (bariatric surgery) services.
Eligibility for NHS Mounjaro: Adults with a BMI of 30 kg/m² or above, or BMI of 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, dyslipidaemia, sleep apnoea, or cardiovascular disease history) may be eligible. For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds (BMI 27.5+) may apply due to higher metabolic health risks at lower weights.
Referral process: Request a referral from your GP to the specialist weight management service in your integrated care board (ICB) area. Services are tier 3 or tier 4—not available in primary care. Regional availability and waiting lists vary; some areas may have waits of many months.
Assessment: Once referred, you'll be assessed by a multidisciplinary team (doctors, nurses, dietitians) to confirm suitability, rule out contraindications, and establish baseline health markers before commencing Mounjaro pens.
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 to Mounjaro Pens in the UK
NHS route: Free at point of use once prescribed by a specialist service; covers all doses and pens. However, access is limited by regional capacity and funding. Many ICBs have lengthy waiting lists or restricted access criteria. You must be referred and assessed by a tier 3 service—your GP cannot prescribe directly.
Private route: Available through GPhC-registered online prescribing services following a clinical assessment with a UK-licensed prescriber. Typically faster access (days to weeks) and available without NHS referral. Costs vary by dose: approximately £129–£320 per month depending on the Mounjaro pen strength and provider. Both NHS and private prescriptions are dispensed through UK registered pharmacies and the same KwikPen device is used.
Use our free GLP-1 weight loss calculator to estimate potential weight loss outcomes at different Mounjaro doses, and our BMI calculator to confirm your eligibility range.
- 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.
Can my GP prescribe Mounjaro pens on the NHS?
No. GPs cannot prescribe Mounjaro through standard primary care. It is only available through NHS tier 3 (specialist) weight management services. You must be referred by your GP to your local integrated care board's specialist service for assessment and prescribing.
How long are NHS waiting lists for Mounjaro pens?
Waiting times vary significantly by region and ICB. Some areas have waits of 6–18 months; others may have shorter or longer delays depending on service capacity and funding. Contact your local weight management service for your specific waiting time after referral.
What is a Mounjaro KwikPen and how does it work?
A KwikPen is a pre-filled auto-injection pen containing four weekly doses of Mounjaro. Each pen covers one month of treatment. You inject once weekly into the stomach, thigh, or upper arm. The needle is hidden, and injection takes just a few seconds. Each new pen is stored in the fridge until use.
What happens if I cannot access Mounjaro through the NHS?
Private prescribing through UK-licensed online services is an alternative route. You complete a clinical assessment, and if approved by a prescriber, you receive a prescription dispensed by a registered pharmacy. This route is faster (typically 1–2 weeks) but costs approximately £129–£320 per month depending on dose.
Are there any other GLP-1 weight loss injections available on the NHS?
Yes. Saxenda (liraglutide) is also available through NHS tier 3 services, though access is similarly limited. Wegovy (semaglutide) eligibility and NHS availability vary by region. All three are prescription-only and require specialist assessment. Your GP or specialist service can discuss which option is most appropriate for you. ```
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.