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- 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: Dosage, Cost, and UK Access
Choosing between Wegovy and Mounjaro for weight management involves understanding their dosing schedules, costs, and how to access them in the UK. Both are prescription-only GLP-1 and GIP/GLP-1 receptor agonist medications, but they differ significantly in their dosing routes, escalation timelines, and pricing. This guide compares the two side by side to help you understand what's involved in accessing either medication through NHS specialist services or private online prescribing in the UK.
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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.
Wegovy and Mounjaro Dosage Comparison
Wegovy (semaglutide) starts at 0.25 mg once weekly and escalates over 16 weeks to a maximum of 2.4 mg. Mounjaro (tirzepatide) starts at 2.5 mg once weekly and escalates over 20 weeks to a maximum of 15 mg. Both are once-weekly injections, though the dose ranges differ substantially.
Wegovy's dose titration schedule is: 0.25 mg (weeks 1–4), 0.5 mg (weeks 5–8), 1 mg (weeks 9–12), 1.7 mg (weeks 13–16), then 2.4 mg (week 17 onwards). Mounjaro's schedule is: 2.5 mg (weeks 1–4), 5 mg (weeks 5–8), 7.5 mg (weeks 9–12), 10 mg (weeks 13–16), 12.5 mg (weeks 17–20), then 15 mg (week 21 onwards). Clinical trials showed Mounjaro delivered an average weight loss of 15–21% of body weight, whilst Wegovy achieved approximately 15% on average—though individual results vary significantly. Use our GLP-1 weight loss calculator to estimate potential outcomes at different doses based on your starting weight.
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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 Cost and Private Access Routes
Private prescription costs for Wegovy typically range from £130–£280 per month depending on dose, whilst Mounjaro generally costs £150–£320 monthly. These costs reflect the dose you're taking, as each KwikPen or auto-injection pen contains a month's supply. Accessing either medication privately involves an online consultation with a UK-licensed prescriber, who will assess your eligibility based on your BMI and health profile. If approved, your prescription is dispensed by a GPhC-registered pharmacy and delivered to you. NHS access is limited to tier 3 specialist weight management services through GP referral, but availability and waiting times vary significantly by region and ICB funding decisions. Many areas have substantial waiting lists or limited access to weight loss medications. Private prescribing offers faster access but requires direct payment.
- 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's the difference between Wegovy and Mounjaro doses?
Wegovy's maximum dose is 2.4 mg once weekly, escalating over 16 weeks. Mounjaro's maximum is 15 mg once weekly, escalating over 20 weeks. Although the numbers appear different, they reflect different chemical mechanisms—Wegovy is a single GLP-1 agonist, whilst Mounjaro is a dual GIP/GLP-1 agonist. Direct dose comparisons aren't clinically equivalent; your prescriber will advise which is suitable for you.
How much does Wegovy cost privately in the UK?
Private Wegovy costs typically £130–£280 per month depending on the dose you're taking. Costs vary between private prescribers and pharmacies, so it's worth comparing options. Each KwikPen contains four weeks' worth of injections at your current dose.
Is Mounjaro or Wegovy available on the NHS?
Both are available through NHS specialist tier 3 weight management services, but access varies significantly by region. Many areas have waiting lists of months or years. Your GP can refer you, but eligibility and availability depend on your local ICB commissioning decisions. Private access is usually faster but involves direct payment.
How long does it take to reach the maximum dose?
Wegovy reaches maximum dose (2.4 mg) in 16 weeks. Mounjaro takes 20 weeks to reach maximum (15 mg). Both require at least 4 weeks at each dose before increasing. If you experience side effects, escalation can be slowed or paused at your prescriber's discretion.
Can I switch from Wegovy to Mounjaro or vice versa?
Switching between medications is possible but must be managed by your prescriber. There's no official clinical conversion chart, though approximate equivalences exist (e.g., Mounjaro 10 mg ≈ Wegovy 1.7 mg). Any switch requires a new clinical assessment and prescription. Never stop one medication and start another without guidance.
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