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 Prices and Wegovy Comparison in the UK
If you're considering Mounjaro or Wegovy for weight management in the UK, understanding the pricing and differences between these two prescription injections is essential. Mounjaro (tirzepatide) 5mg is typically the first maintenance dose after the starting phase, while Wegovy (semaglutide) uses different dose escalations. Both are available through NHS specialist services or private prescription routes, and costs vary significantly depending on your access method and provider. This guide compares the two options factually so you can make an informed decision with your healthcare provider.
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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.
Clinical Trial Results and Mechanism Differences
The key difference between these medications lies in their mechanism: Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1 agonist only. In the SURMOUNT-1 clinical trial, participants on Mounjaro 5mg achieved average weight loss of approximately 15% of body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity. The STEP-1 trial for Wegovy showed average weight loss of approximately 14.9% at the maximum 2.4mg dose. Individual results vary significantly — some people respond better to one medication than the other, which is why a prescriber's assessment is crucial.
Mounjaro titration: 2.5mg (weeks 1–4), then 5mg (weeks 5–8+), escalating to 15mg maximum. Wegovy titration: 0.25mg (weeks 1–4), escalating to 2.4mg maximum. The different starting points reflect their different potencies and mechanisms.
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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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UK Pricing, Access Routes, and Prescriber Assessment
In the UK, both medications are available through NHS specialist tier 3 weight management services (eligibility varies by region and waiting lists can be lengthy) or through private prescription routes following an online clinical assessment with a UK-licensed prescriber. Private costs typically range from £129–£320 per month depending on dose and provider. Each KwikPen contains 4 weekly doses. Your GP can assess whether you meet eligibility criteria — generally a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Use our free BMI calculator above to check your starting point, and our GLP-1 weight loss calculator to see potential outcomes at different doses.
- 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.
Why is Mounjaro 5mg the first maintenance dose if it starts at 2.5mg?
Mounjaro titration begins at 2.5mg for 4 weeks to allow your body to adjust and minimise nausea. At week 5, you increase to 5mg, which is the first full maintenance dose. You remain on 5mg until your prescriber assesses whether you need further escalation based on weight loss and tolerability.
How does Mounjaro 5mg compare to Wegovy in terms of weight loss?
In clinical trials, Mounjaro 5mg achieved approximately 15% average weight loss, while Wegovy at maximum dose (2.4mg) achieved approximately 14.9%. However, these are averages — individual results vary significantly. Some people respond better to one medication than the other, which is why prescriber assessment is essential.
Can I get Mounjaro 5mg on the NHS in the UK?
Yes, tirzepatide (Mounjaro) is now approved by NICE for use within NHS specialist tier 3 weight management services. However, access varies significantly by region (ICB), and waiting lists can be very long in many areas. Your GP can refer you to your local service.
What's the typical cost difference between Mounjaro 5mg and Wegovy private prescriptions?
Private costs for both medications typically range from £129–£320 per month depending on dose, provider, and whether you're escalating or on a maintenance dose. Mounjaro's dual mechanism may cost slightly more at comparable effectiveness levels, but prices vary by pharmacy and are competitive across providers.
How do side effects at Mounjaro 5mg compare to Wegovy?
Both medications cause similar common side effects (nausea, diarrhoea, constipation, stomach pain) that typically decrease over time. Mounjaro's dual mechanism means some people experience slightly different effects, but individual tolerability varies greatly. Your prescriber will monitor you and can adjust doses if needed.
Ready to take control of your weight loss journey?
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