The UK's most complete GLP-1 guide
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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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Mounjaro 5th Dose vs Wegovy — How They Compare in the UK
The 5th dose of Mounjaro represents the first escalation to 10mg — a key point in the UK prescription weight loss journey. If you're comparing Mounjaro at this stage with Wegovy, it's helpful to understand how these two GLP-1 medications differ in dosing, mechanism, and expected outcomes. Both are prescription weight loss injections available in the UK following clinical assessment, but they work differently. This guide breaks down what happens at the 5th Mounjaro dose and how it compares directly with Wegovy's approach, helping you understand what your prescriber might recommend.
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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.
Understanding Mounjaro's 5th Dose Schedule
Mounjaro follows a specific dose titration schedule. The 5th dose represents week 17, when you move from 7.5mg to 10mg — your first real escalation into the higher therapeutic range. This happens only if your prescriber confirms it's appropriate based on your response and tolerability.
Mounjaro KwikPen dosing timeline:
- Doses 1–4: 2.5mg (weeks 1–4), then 5mg (weeks 5–8)
- 5th dose onwards: 7.5mg (weeks 9–12), then 10mg (weeks 13–16)
- Further escalation: 12.5mg and 15mg possible if needed
At the 5th dose, you've had tirzepatide in your system for roughly four months. Clinical trial data suggests this is when weight loss typically becomes more noticeable, as your body has fully adapted to the medication. Unlike Wegovy, Mounjaro works through a dual GIP and GLP-1 mechanism, which some prescribers believe may produce stronger appetite suppression at equivalent therapeutic doses.
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Mounjaro 10mg vs Wegovy: Direct Comparison
At the 5th Mounjaro dose (10mg), you're approaching mid-range efficacy. Wegovy reaches its maximum at 2.4mg — so the two medications are not at comparable therapeutic levels at this point. However, clinical trial data shows meaningful differences:
- Mounjaro 10mg: Average weight loss ~19.5% body weight (SURMOUNT-1 trial)
- Wegovy 2.4mg: Average weight loss ~14.9% body weight (STEP-1 trial)
This suggests Mounjaro may produce greater average weight loss, though individual results vary significantly. Prescription weight loss in the UK requires ongoing prescriber oversight — your GP or specialist will monitor your progress and decide whether to continue, adjust, or switch medications. Both require NHS Nice guidance eligibility or private prescription following clinical assessment.
- 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 5th dose of Mounjaro?
The 5th dose is week 17 of treatment, when Mounjaro escalates from 7.5mg to 10mg. This is your first meaningful dose increase and represents roughly four months of consistent treatment. Your prescriber will only escalate if you've tolerated the previous dose well and your weight loss is progressing as expected.
How does Mounjaro's dosing compare to Wegovy?
Mounjaro escalates across five doses (2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg maximum). Wegovy escalates across five doses (0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg maximum). Mounjaro's 10mg dose is roughly equivalent to Wegovy's 1.7mg in therapeutic strength, not Wegovy's maximum.
Which produces better weight loss — Mounjaro or Wegovy?
Clinical trials show Mounjaro may produce slightly greater average weight loss than Wegovy, but individual results vary widely. At your 5th Mounjaro dose (10mg), you're likely experiencing stronger effects than someone on Wegovy's maintenance dose. Your prescriber will assess which is best for your specific health profile.
Can my prescriber switch me from Mounjaro to Wegovy at the 5th dose?
Yes, prescribers can switch between weight loss injections if you're not responding well or experiencing unmanageable side effects. However, this is an individual decision requiring clinical assessment. There's no standard conversion — your prescriber will restart you on Wegovy's titration schedule. Always discuss concerns with your GP or online prescriber before any switch.
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