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
Can UK Doctors Prescribe Mounjaro?
Yes, UK doctors can prescribe Mounjaro (tirzepatide), but through specific pathways. The NHS approves tirzepatide for specialist weight management services following NICE guidance, while private prescribers can issue prescriptions following an online clinical assessment. Eligibility depends on your BMI, health conditions, and whether you're accessing the medication through NHS or private routes. Understanding how the UK prescribing system works helps you explore the right option for your situation.
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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 Prescribing and NICE Approval for Mounjaro
NICE approved tirzepatide (Mounjaro) for NHS use in June 2024 as part of the specialist weight management pathway. However, NHS access is not through your GP directly — instead, you'll need referral to a tier 3 or tier 4 specialist weight management service.
- Tier 3 services are hospital-based multidisciplinary weight management clinics available in most regions
- Tier 4 services are specialist centres offering bariatric surgery and advanced interventions
- Your GP can refer you, but NHS availability and waiting lists vary significantly by region (ICB)
- Some regions have waiting lists of several months to over a year for specialist assessment
Once assessed by a specialist, Mounjaro may be prescribed if you meet eligibility criteria: BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, or sleep apnoea). For South Asian, Black African, Black Caribbean, and Chinese adults, lower BMI thresholds apply — eligibility may start at BMI 27.5 or above due to higher health risks at lower weights.
Use our free BMI calculator above to check your starting point and understand your potential eligibility.
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 to Mounjaro in the UK
NHS route: Free at point of use but requires GP referral to specialist services, clinical assessment, and can involve substantial waiting times. Available only through tier 3/4 services in your region — postcode matters significantly.
Private route: Faster access — typically within days of online consultation. You'll complete an assessment with a UK-licensed prescriber, and if appropriate, receive a prescription dispensed by a GPhC-registered pharmacy. Private prescriptions cost approximately £129–£320 monthly depending on dose. No NHS referral needed.
Both routes require a clinical assessment before prescription. Your medical history, current medications, contraindications (such as pregnancy or severe gastroparesis), and health conditions are evaluated to ensure Mounjaro is safe and suitable for you. Neither route assures prescription — suitability is determined individually.
- 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?
No, not typically. GPs cannot prescribe Mounjaro on the NHS — it must be prescribed through a specialist tier 3 or tier 4 weight management service. Your GP can refer you to these services, but the prescription decision rests with the specialist team. Private prescribers (online consultations with UK-licensed doctors) can prescribe Mounjaro following a clinical assessment.
How long is the NHS wait for Mounjaro?
NHS waiting times vary dramatically by region. Some areas have waits of 3–6 months, whilst others exceed 12 months or longer. Contact your local specialist weight management service for a realistic timeline. Private routes typically offer faster access — usually within days to a few weeks of assessment.
What BMI do I need to be prescribed Mounjaro on the NHS?
You typically need a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, high blood pressure, cardiovascular disease, sleep apnoea). South Asian, Black African, Black Caribbean, and Chinese adults have lower thresholds — eligibility may start at BMI 27.5. Use our free BMI calculator to check yours.
Is Mounjaro available on the NHS everywhere in the UK?
Mounjaro is approved by NICE for NHS use, but availability and prescribing varies significantly by region (ICB). Some areas have well-resourced services; others have limited capacity or long waiting lists. Check with your GP or local specialist weight management service to confirm availability in your area.
What happens after my clinical assessment for Mounjaro?
If approved, you'll receive a prescription and dosing plan. Mounjaro starts at 2.5 mg weekly, with increases every 4 weeks (5 mg, 7.5 mg, 10 mg, 12.5 mg, up to 15 mg maximum). You'll be monitored for side effects and weight loss progress. Your doctor or prescriber will advise on how long treatment continues — typically ongoing, with regular reviews.
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.