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 10mg vs Wegovy in the UK
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight loss injections available in the UK, but they work differently. Mounjaro uses a dual mechanism targeting both GIP and GLP-1 pathways, while Wegovy targets GLP-1 only. At the 10mg Mounjaro dose, you're in the mid-range of titration, while Wegovy's maximum is 2.4mg. This guide explains the key differences, trial evidence, and how your prescriber decides which suits you best.
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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.
How Mounjaro 10mg and Wegovy Compare
Mechanism: Mounjaro is a dual GIP + GLP-1 receptor agonist, meaning it activates two natural hormone pathways. Wegovy is a GLP-1-only agonist. This dual action in Mounjaro may explain why some clinical data shows slightly higher average weight loss, though individual results vary significantly.
Trial evidence: In the SURMOUNT-1 trial, tirzepatide at 10mg achieved average weight loss of approximately 19.5% body weight. Wegovy showed approximately 14.9% average weight loss in STEP-1 trials at its maximum 2.4mg dose. Both were used alongside reduced-calorie diet and increased physical activity — medication alone does not produce these results.
Dosing: Mounjaro 10mg is a mid-range maintenance dose (escalated from 2.5mg over 12+ weeks). Wegovy reaches its maximum at 2.4mg. This makes direct dose comparison difficult — they are not equivalent strengths.
Injection schedule: Both are once-weekly injections, supplied as pre-filled pens. Both require storage in a refrigerator until opened.
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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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Which Medication Is Right for You?
Your GP or prescriber will assess your individual health profile, weight loss goals, and any existing medical conditions to determine suitability. Neither medication is universally "better" — clinical trial averages do not predict personal outcomes. Factors considered include your BMI, whether you have weight-related health conditions like type 2 diabetes, previous weight loss attempts, and any contraindications.
Both require a prescription and clinical assessment. If you're eligible for NHS specialist weight management services, availability depends on your regional ICB. Private prescribers can assess both options without NHS referral. Use our free GLP-1 weight loss calculator to estimate potential results, and our BMI calculator to check your current BMI category — both tools help inform conversations with your prescriber.
- 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.
Is Mounjaro 10mg stronger than Wegovy 2.4mg?
They use different mechanisms, so "stronger" isn't straightforward. Mounjaro 10mg showed ~19.5% average weight loss in trials; Wegovy 2.4mg showed ~14.9%. However, individual results vary widely. They're not directly comparable doses — your prescriber considers your personal health when choosing between them.
Can I switch from Wegovy to Mounjaro 10mg?
Switching between medications is possible but must be managed by your prescriber. There is no official conversion chart. If considering a switch, discuss with your GP or the prescriber who issued your current prescription. They'll assess whether a switch is clinically appropriate and manage any transition safely.
Which has fewer side effects, Mounjaro or Wegovy?
Both share common side effects: nausea, diarrhoea, vomiting, and stomach pain are very common with both. Individual tolerability varies. Some people tolerate one better than the other. Your prescriber can discuss side effect profiles in the context of your medical history and any other medications you take.
How do I access Mounjaro 10mg or Wegovy in the UK?
NHS access is through tier 3 specialist weight management services — referral from your GP required. Regional availability varies and waiting lists can be long. Private access is through GPhC-registered online pharmacies following an online clinical assessment. Both routes require a prescription from a UK-licensed prescriber.
Can I get Mounjaro 10mg on the NHS in the UK?
NICE has approved tirzepatide for use in NHS specialist weight management services, but availability depends on your regional ICB and specialist service capacity. Many NHS services have significant waiting lists. Your GP can refer you to specialist services, but eligibility assessment and prescribing occurs at tier 3 level, not in general practice. ```
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