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 Injections on the NHS — How to Access Treatment in the UK
Mounjaro (tirzepatide) is a prescription-only weight management injection that can be accessed through the NHS in the UK, though availability varies significantly by region. NICE has approved tirzepatide for use within specialist weight management services, and it's now available on prescription in many areas. However, NHS access typically requires referral to a tier 3 or tier 4 specialist weight management service, and waiting lists can be substantial. This guide explains how the NHS pathway works, who is eligible, and what to expect.
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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 the Tier 3 Weight Management Pathway
The NHS prescribes Mounjaro through specialist weight management services, not standard GP prescription. To be eligible, you typically need:
- A BMI of 30 kg/m² or above, or BMI of 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, dyslipidaemia, sleep apnoea, cardiovascular disease)
- Previous attempts at weight loss through lifestyle changes
- Referral to your local NHS tier 3 weight management service via your GP
- Ethnicity-adjusted thresholds: those of South Asian, Chinese, Black African, or Caribbean heritage may be eligible at BMI 27.5 or above
NICE guidance supports tirzepatide as an option within tier 3 and tier 4 services. However, availability depends on your local Integrated Care Board (ICB) funding and commissioning decisions. Some areas have established pathways; others do not yet commission tirzepatide. Your GP can advise whether your region currently offers this treatment. Our GLP-1 weight loss calculator can help estimate potential weight loss outcomes at different Mounjaro doses alongside lifestyle changes.
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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 Route — Timelines and Access Differences
NHS route: Free on prescription once approved by your tier 3 service, but referral to assessment can take weeks to months, and treatment initiation may be delayed further depending on local commissioning and stock availability. Many regions have waiting lists of 6–12+ months.
Private route: Faster access — online consultation with a UK-licensed prescriber typically takes 24–48 hours, prescription issued if clinically appropriate, dispensed by a GPhC-registered pharmacy. Private costs range from approximately £129–£320 per month depending on dose. Both routes require a clinical assessment; the NHS route simply involves a specialist rather than an online prescriber. Your GP can discuss both options and the regional NHS position with you.
- 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 I get Mounjaro on the NHS?
Yes, NICE has approved tirzepatide (Mounjaro) for NHS use within specialist weight management services (tier 3 and tier 4). However, availability varies by region and ICB funding. Contact your GP to check if your area commissions Mounjaro and what the referral pathway is.
What is the difference between tier 3 and tier 4 weight management?
Tier 3 is specialist multidisciplinary weight management in the community or outpatient settings, usually the first specialist level. Tier 4 involves more intensive interventions and may include bariatric surgery. Mounjaro is prescribed at both tiers depending on clinical need and local commissioning.
How long is the NHS waiting list for Mounjaro?
Waiting times vary significantly by region. Some areas have waiting lists of 6–12 months or longer for tier 3 assessment and treatment initiation. Ask your GP about your local ICB's current waiting times for weight management services and tirzepatide initiation.
What is the Mounjaro KwikPen and is it available on the NHS?
The Mounjaro KwikPen is the pre-filled injection device containing tirzepatide. On the NHS, you'll receive the same KwikPen device as the private market — each pen contains four weekly doses. Storage is in a fridge (2–8°C) until first use, then room temperature for up to 30 days.
How does Mounjaro dose titration work on the NHS?
Mounjaro starts at 2.5 mg weekly and increases gradually — 5 mg, 7.5 mg, 10 mg, 12.5 mg, and up to 15 mg maximum — with at least 4 weeks on each dose. Your NHS tier 3 team will monitor your response and side effects before escalating. Use our BMI calculator to track your baseline before starting treatment.
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.