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
Is Mounjaro Available On The NHS?
Yes, Mounjaro (tirzepatide) is approved for use within NHS specialist weight management services in the UK. However, NHS access is limited and varies significantly by region. Most adults seeking Mounjaro access it through private prescribing rather than the NHS due to waiting lists and availability constraints. This guide explains NHS eligibility, the referral process, and how to access tirzepatide through both routes. Use our free GLP-1 weight loss calculator to explore potential outcomes with different doses of tirzepatide before discussing options with your GP.
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.
NHS Access To Mounjaro — What You Need To Know
NICE approval: Mounjaro (tirzepatide) was approved by NICE for use within NHS specialist weight management services, making it technically available on the NHS. However, access is highly restricted and variable across the UK.
How NHS access works: You cannot request Mounjaro directly from your GP. Instead, you must be referred to a tier 3 or tier 4 specialist weight management service by your GP. These are regional services that assess complex weight management cases. If the specialist service deems Mounjaro appropriate, they may prescribe it.
Significant barriers: Waiting lists for NHS tier 3 services are extremely long in many areas — often 6 months to 2+ years. Some regions have very limited capacity or do not offer specialist services at all. Even if you're accepted into a service, Mounjaro prescribing may be restricted based on local commissioning decisions and ICB (Integrated Care Board) budgets.
Cost: If prescribed on the NHS, Mounjaro is free at the point of prescription (prescription charge applies in England if eligible).
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.
Private Access To Mounjaro — Faster Alternative
Most UK adults accessing Mounjaro do so privately due to NHS waiting times. Private access involves an online consultation with a UK-licensed prescriber who assesses your medical history and eligibility. If approved, a prescription is issued and dispensed by a GPhC-registered online pharmacy.
Cost: Private Mounjaro costs approximately £129–£200+ per month depending on dose and provider. The Mounjaro KwikPen contains 4 weeks of doses.
Speed: Private prescriptions are typically issued within 24–48 hours if you're approved. Medication is delivered within 2–5 days.
Dose titration: Private prescribers follow the same dose titration protocol as NHS (starting 2.5 mg, escalating weekly). You'll need follow-up consultations to adjust dose safely.
Check your eligibility using our BMI calculator — most adults with a BMI of 30+ or 27+ with weight-related health conditions qualify for assessment.
- 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 directly on the NHS?
No. Your GP cannot prescribe Mounjaro directly. You must be referred to a NHS tier 3 or tier 4 specialist weight management service. Your GP can make this referral, but acceptance and waiting times vary significantly by region. Many areas have waiting lists of 12+ months.
What is the difference between NHS and private Mounjaro access?
NHS access is free but involves long waiting lists and limited availability. Private access is faster (24–48 hours approval typically) but costs £129–£200+ monthly. Both require clinical assessment. Private access does not require an NHS referral.
Am I eligible for NHS Mounjaro?
Potential NHS candidates have a BMI of 30+ (or 27+ with weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease). Eligibility varies by region. Your GP can assess whether referral to specialist services is appropriate. Use our BMI calculator to check your starting point.
How long does Mounjaro take to work?
Weight loss typically becomes noticeable within 4–8 weeks of starting, though some people notice appetite reduction within days. Most significant loss occurs between weeks 8–16 as your body adjusts to each dose increase. Individual results vary considerably.
What are the main side effects of Mounjaro?
Very common side effects include nausea, diarrhoea, constipation, and stomach pain — usually mild and temporary during dose escalation. Less common effects include vomiting, indigestion, and injection site reactions. Most improve over time. Serious side effects (severe stomach pain, gallbladder problems) are rare but require immediate medical attention. ```
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.