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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5mg Mounjaro and NHS Access in the UK
5mg is the first maintenance dose of Mounjaro (tirzepatide) and represents a significant step in your weight management journey following the initial 2.5mg starting dose. If you're exploring Mounjaro through the NHS in the UK, understanding how the 5mg dose fits into NICE guidance and NHS tier 3 specialist services is essential. This guide covers NHS eligibility, prescribing pathways, and what to expect at this dose level, all aligned with current UK health guidelines.
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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 Mounjaro Access in the UK
NICE approval and NHS prescribing: Mounjaro (tirzepatide) is approved by NICE and available through NHS specialist weight management services (tier 3) for eligible adults. The 5mg dose is typically reached around weeks 5–8 of treatment, following the initial 2.5mg dose.
Who qualifies for NHS Mounjaro: You may be eligible if you have a BMI of 30 kg/m² or above, or BMI of 27–29.9 kg/m² with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea, or cardiovascular disease). For South Asian, Chinese, Black African, and Black Caribbean adults, lower BMI thresholds apply — eligibility may start at BMI 27.5 or above due to higher health risks at lower weights.
NHS access route: NHS Mounjaro is accessed through referral to a tier 3 specialist weight management service via your GP. This is not a standard GP prescription — your GP refers you to a specialist team who will assess your suitability, initiate treatment, and manage dose titration. Waiting times vary significantly by region (ICB), with some areas experiencing months-long waiting lists.
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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.
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NHS vs Private Access for 5mg Mounjaro in the UK
NHS pathway advantages: Free prescription costs (you pay only standard NHS prescription charges), medical oversight by specialists, and integrated diabetes/cardiovascular support if needed. However, NHS access is limited by regional availability and waiting times can be lengthy.
Private pathway: If NHS waiting lists are prohibitive, Mounjaro is available through GPhC-registered online prescribing services following a clinical consultation. Private costs typically range from £129–£320+ per month depending on dose. At 5mg, you'll remain on a private prescription until your prescriber assesses readiness for dose escalation, usually after at least 4 weeks at this level. Both routes require ongoing clinical oversight and lifestyle changes (reduced-calorie diet and increased physical activity) alongside the medication.
- 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.
How long do you stay on 5mg Mounjaro before increasing?
At least 4 weeks. MHRA guidance recommends a minimum of 4 weeks at each dose before escalating. Your prescriber will assess your response, side effects, and tolerability before moving to 7.5mg. If you're tolerating 5mg well and progressing toward your weight loss goal, you may continue longer before escalating.
Is 5mg Mounjaro enough for weight loss?
In clinical trials, participants at 5mg showed meaningful weight loss — approximately 12–15% body weight reduction on average alongside lifestyle changes. However, individual results vary significantly. Some people achieve their goals at 5mg; others may benefit from dose escalation. Your prescriber will assess your progress and discuss options with you.
What side effects are common at 5mg Mounjaro?
The most common side effects at 5mg are nausea, diarrhoea, constipation, and reduced appetite — these typically ease as your body adapts. GI side effects are more pronounced during dose escalation weeks but often improve within a few days. Serious side effects are rare but include severe stomach pain (possible pancreatitis) — seek immediate medical attention if this occurs.
Can I get 5mg Mounjaro through the NHS while waiting for tier 3?
If you're on an NHS waiting list for specialist services, your GP cannot prescribe Mounjaro in primary care — it must be initiated and managed by the tier 3 specialist team. If waiting times are unacceptable, you may explore private prescribing options while remaining on the NHS list, but discuss this with your GP first.
How does 5mg Mounjaro compare to Wegovy at equivalent doses?
Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is GLP-1 only. Clinical trials suggest Mounjaro may produce slightly larger average weight loss, but individual responses vary. The 5mg Mounjaro dose is approximately equivalent to 1.7mg Wegovy, though any medication switch must be managed by your prescriber — there is no direct conversion formula.
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