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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Wegovy vs Mounjaro Dosing in the UK
Both Wegovy and Mounjaro are prescription-only weight loss injections available in the UK, but their dosing schedules differ significantly. Wegovy (semaglutide) and Mounjaro (tirzepatide) work through different mechanisms and require different titration protocols. Understanding the dosing differences is important for anyone considering these medications through NHS specialist services or private prescribing. This guide compares how each medication is dosed and what you can expect during treatment in the UK healthcare context.
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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.
Dosing Schedules: Wegovy vs Mounjaro
Wegovy (semaglutide) starts at 0.25 mg once weekly and increases gradually over approximately 16–20 weeks to a maximum dose of 2.4 mg. Each dose is held for 4 weeks before increasing, making the titration period longer than Mounjaro.
Mounjaro (tirzepatide) starts at 2.5 mg once weekly and escalates to a maximum of 15 mg over a similar timeframe, but with more dose steps available. Because Mounjaro is a dual GIP and GLP-1 agonist rather than a single GLP-1 agonist, even the starting dose produces noticeable effects for many users.
- Wegovy: 0.25 mg → 0.5 mg → 1 mg → 1.7 mg → 2.4 mg (five steps total)
- Mounjaro: 2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg (six dose levels)
Both are once-weekly injections, but Mounjaro offers more granular dose adjustments, which may help prescribers tailor treatment more precisely to individual response and tolerability.
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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 Access and NICE Guidance for Weight Loss Injections
The NHS has approved both Wegovy and Mounjaro through NICE guidance for use in specialist tier 3 weight management services. Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, hypertension, or cardiovascular disease. However, NHS access varies significantly by region—some integrated care boards (ICBs) have long waiting lists, while others may have limited availability.
Many people choose private prescribing instead, where a UK-licensed prescriber assesses eligibility following an online consultation. Private costs range from £129–£320 monthly depending on the dose. Regardless of route, both medications require a prescription and clinical assessment to confirm suitability. Use our GLP-1 weight loss calculator to explore projected outcomes at different doses, and our BMI calculator to check your current health context.
The NHS has approved both Wegovy and Mounjaro through NICE guidance for use in specialist tier 3 weight management services. Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, hypertension, or cardiovascular disease. However, NHS access varies significantly by region—some integrated care boards (ICBs) have long waiting lists, while others may have limited availability.
Many people choose private prescribing instead, where a UK-licensed prescriber assesses eligibility following an online consultation. Private costs range from £129–£320 monthly depending on the dose. Regardless of route, both medications require a prescription and clinical assessment to confirm suitability. Use our GLP-1 weight loss calculator to explore projected outcomes at different doses, and our BMI calculator to check your current health context.
- 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.
What is the key difference between Wegovy and Mounjaro dosing?
Wegovy titrates from 0.25 mg to a maximum of 2.4 mg over about 16–20 weeks, with five dose steps. Mounjaro starts at 2.5 mg and escalates to 15 mg with six dose levels. Mounjaro offers more granular dose adjustments and typically requires a shorter titration period.
How long does it take to reach the maximum dose on each medication?
Both medications require a minimum of 4 weeks at each dose before escalating. Wegovy typically reaches maximum (2.4 mg) around week 16–20, while Mounjaro can reach 15 mg over a similar timeframe but with more intermediate steps available.
Can I access Wegovy or Mounjaro through the NHS in the UK?
Yes, both are available through NHS tier 3 specialist weight management services following NICE approval. However, access depends on your regional ICB and local waiting lists. Many people opt for private prescribing as an alternative route, which does not require NHS referral.
Is one medication more effective than the other for weight loss?
Clinical trials show both are effective. Mounjaro demonstrated approximately 15–21% average body weight loss, while Wegovy showed around 14.9% in STEP trials. Individual results vary significantly, and prescriber experience with each medication may influence which is recommended for you.
What happens if I cannot tolerate a higher dose of Wegovy or Mounjaro?
Your prescriber can pause escalation or maintain you at a lower, more tolerable dose. Some people respond well at moderate doses (e.g., Wegovy 1 mg or Mounjaro 7.5 mg). Dose adjustment is based on your individual tolerance and health response, not a fixed schedule.
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.