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
Mounjaro 5mg Injection — NHS UK Prescribing Guide
The 5mg dose is the first maintenance step in Mounjaro treatment following the starter dose of 2.5mg. In the UK, access to this weight loss injection is available through NHS specialist tier 3 weight management services or privately following a clinical assessment. NICE has approved tirzepatide (Mounjaro) for use within NHS weight management pathways for eligible adults. Understanding how Mounjaro 5mg works within UK prescribing guidelines can help you make informed decisions about whether this treatment might be right for you. You can use our free GLP-1 weight loss calculator to estimate potential results at different doses, and our BMI calculator to check your current health category.
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 Eligibility and Tier 3 Access for Mounjaro 5mg
In the UK, Mounjaro is prescribed within NHS tier 3 specialist weight management services, not by standard GPs. Eligibility criteria include a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with at least one weight-related health condition such as type 2 diabetes, hypertension, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may qualify at lower BMI thresholds (from 27.5 kg/m²) because these groups face higher metabolic risks at lower weights.
The 5mg dose represents the first maintenance step — you'll start on 2.5mg for weeks 1–4, then progress to 5mg from week 5 onwards. NICE guidance supports tirzepatide within weight management pathways for eligible patients. However, NHS availability varies significantly by region and integrated care board (ICB). Many areas have long waiting lists for tier 3 services. Your GP can refer you to your local tier 3 service, though access is not assured in all regions.
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 for Mounjaro 5mg
NHS route: Referral through your GP to a tier 3 specialist weight management service. No cost at point of use, but availability and waiting times vary widely by region. Some areas may not have tier 3 services available.
Private route: A UK-licensed prescriber can assess you online and issue a prescription if clinically appropriate, dispensed by a GPhC-registered pharmacy. No waiting list, but costs apply (typically £129–£200 per month depending on dose). Both routes require a clinical assessment before dispensing. Track your progress once started using our free progress tracker to monitor weight changes and side effect patterns alongside your healthcare provider's guidance.
- 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.
Is Mounjaro 5mg available on the NHS in the UK?
Mounjaro (tirzepatide) is available through NHS tier 3 specialist weight management services for eligible adults. However, availability, waiting times, and prescribing criteria vary significantly by region. Ask your GP about referral to your local tier 3 service, but be aware that not all areas may have services available or funded access.
How long do I stay on Mounjaro 5mg before increasing to the next dose?
The standard guidance is to stay on each dose for a minimum of 4 weeks before progressing. Most patients remain on 5mg for weeks 5–8 before potentially escalating to 7.5mg in week 9, depending on weight loss progress and tolerability. Your prescriber will advise on your individual schedule.
What weight loss can I expect from Mounjaro 5mg?
Clinical trials showed that Mounjaro at 5mg produced average weight loss of approximately 15% of body weight over 72 weeks, though individual results vary considerably. Weight loss depends on dose, adherence, dietary changes, physical activity, and personal metabolism. Our GLP-1 calculator can give you an estimate based on your starting weight.
Is Mounjaro 5mg the maximum dose I can take?
No — 5mg is the first maintenance dose. The maximum approved dose in the UK is 15mg weekly. Doses progress from 2.5mg (starter) through 5mg, 7.5mg, 10mg, 12.5mg to 15mg, with at least 4 weeks between each increase. Your prescriber determines your progression based on tolerability and weight loss response.
What happens if I can't access Mounjaro through the NHS?
If NHS tier 3 services are unavailable in your area or waiting times are too long, you can access Mounjaro privately through a UK-licensed prescriber. An online clinical assessment determines suitability, and a prescription is dispensed by a GPhC-registered pharmacy if approved. Private prescribing is faster but involves costs.
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.