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 5mg — UK NHS Prescription Information
Mounjaro 5mg is the first standard maintenance dose of tirzepatide, a prescription-only weight management injection licensed in the UK. After starting on the 2.5mg starter dose for four weeks, adults typically move to 5mg once weekly. This guide explains NHS eligibility criteria, how the 5mg dose fits into the titration schedule, and what to expect at this stage of treatment in the UK healthcare context.
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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 5mg in UK Services
NHS access to Mounjaro (tirzepatide) in the UK is available through specialist tier 3 weight management services, typically following referral from your GP. NICE has approved tirzepatide for use within these services for eligible adults.
You may be eligible if you have:
- A BMI of 30 kg/m² or above, OR
- A BMI of 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, high blood pressure, abnormal blood fats, sleep apnoea, or cardiovascular disease)
- For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply (BMI 27.5 or above)
The 5mg dose is typically reached after four weeks on 2.5mg. NHS services manage dose titration gradually to minimise side effects and monitor your response. Availability and waiting times vary significantly by region and integrated care board (ICB).
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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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
What Happens at 5mg — Dose and Effects
At the 5mg maintenance dose, the tirzepatide dose has doubled from the starter dose. Clinical trial data suggests that 5mg may support weight loss of approximately 15% of body weight on average, though individual results vary significantly and depend on diet, physical activity, and personal factors.
At this dose, you'll continue with one injection per week, using a Mounjaro KwikPen. Side effects like nausea often improve as your body adjusts, though some people experience ongoing digestive effects. Your GP or specialist will monitor your progress at regular clinic appointments and may recommend dose escalation to 7.5mg after another four weeks if appropriate for your individual response.
- 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 does the 5mg dose compare to the starter dose?
The 2.5mg starter dose is taken for the first four weeks to allow your body to adjust. The 5mg dose doubles this, and is the first standard maintenance dose where weight loss effects typically become more noticeable. You stay on 5mg for at least four weeks before any further increase.
Can I get Mounjaro 5mg on the NHS in the UK?
Yes, tirzepatide (Mounjaro) is NICE-approved for NHS specialist weight management services. Access is through tier 3 services following GP referral. However, availability and waiting times vary significantly by region. Waiting lists can be very long in some areas.
What weight loss might I expect at 5mg?
Clinical trials showed an average loss of around 15% of body weight at 5mg after 72 weeks, alongside dietary changes and increased physical activity. However, individual results vary considerably. Use our free GLP-1 weight loss calculator to estimate potential outcomes based on your starting weight and dose.
What if I experience side effects at 5mg?
Common side effects like nausea, diarrhoea, and constipation often improve over time as your body adjusts. If side effects are severe, inform your NHS specialist immediately. They may recommend staying on 5mg longer before escalating, or adjusting your diet to manage symptoms.
How is Mounjaro 5mg different from Wegovy?
Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy is a GLP-1 agonist only. Mounjaro 5mg is roughly equivalent to Wegovy 1.7mg in terms of effect, though both medications have different action mechanisms. Your prescriber will choose based on your individual health profile.
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.