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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What is 5mg Mounjaro in ML?
The 5mg dose of Mounjaro (tirzepatide) is typically your first maintenance dose after the initial 2.5mg starting period. Mounjaro comes pre-filled in KwikPen devices, and each pen delivers a fixed volume of the injection — not millilitres. This guide explains how Mounjaro dosing works in the UK, NHS eligibility criteria, and what to expect from the 5mg dose in clinical context. Use our free GLP-1 weight loss calculator to explore how different Mounjaro doses may support your weight management journey.
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Calculate Your BMI Instantly
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.
How Mounjaro Dosing Works — The 5mg Step
Mounjaro is supplied in pre-filled KwikPen devices, not measured in millilitres — each pen contains a complete 4-week dose of tirzepatide at a specific strength. The 5mg dose is typically the first maintenance strength you'll use after starting on 2.5mg for 4 weeks. In clinical trials (SURMOUNT-1), the 5mg dose helped participants lose an average of approximately 15% of their body weight alongside a reduced-calorie diet and increased physical activity — though individual results vary significantly.
- Each KwikPen contains four weekly doses (4 weeks' supply)
- You inject once weekly on the same day each week
- Minimum 4 weeks on 5mg before escalating to 7.5mg
- The dose can be escalated every 4 weeks if tolerated, up to the maximum of 15mg
- 5mg is not the maximum dose — many people escalate further for additional benefit
The 5mg Mounjaro dose works as a dual GIP and GLP-1 receptor agonist, activating two hormone pathways simultaneously to regulate appetite and food intake. This is different from single-mechanism GLP-1 injections like Wegovy (semaglutide).
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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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS Eligibility and Access in the UK
In the UK, Mounjaro (tirzepatide) is available through NHS specialist tier 3 weight management services and via private prescription following an online clinical assessment. NHS eligibility typically requires a BMI of 30 kg/m² or above, or BMI of 27–29.9 with at least one weight-related health condition (type 2 diabetes, high blood pressure, high cholesterol, or sleep apnoea). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the thresholds are lower — eligibility may begin at BMI 27.5 or above.
- NHS access: Referral to specialist weight management tier 3 service from your GP
- Private access: Online consultation with UK-licensed prescriber, dispensed by GPhC-registered pharmacy
- Individual assessment required before prescription — suitability is not assured
Calculate your BMI instantly using our free BMI calculator to understand where you stand against NHS eligibility thresholds.
- 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 5mg Mounjaro available on the NHS?
Mounjaro, including the 5mg dose, is available on the NHS through specialist tier 3 weight management services for eligible adults. However, NHS availability varies significantly by region and local Integrated Care Board (ICB) funding. Your GP can refer you to your local specialist service if you meet eligibility criteria. Waiting lists can be several months in some areas.
What is the difference between 5mg Mounjaro and 5mg Wegovy?
There is no direct "5mg Wegovy" dose — Wegovy's maximum dose is 2.4mg weekly. Mounjaro's 5mg dose produces different clinical effects because tirzepatide is a dual GIP/GLP-1 agonist, whereas Wegovy (semaglutide) is a single GLP-1 agonist. Clinical trials showed 5mg Mounjaro produced approximately clinically studied weight loss on average, compared to roughly 14.9% for 2.4mg Wegovy, though individual results vary.
How long does it take to reach the 5mg Mounjaro dose?
You start at 2.5mg for 4 weeks, then move to 5mg in week 5. So you'll reach the 5mg dose approximately one month after beginning treatment. Your prescriber may keep you at 5mg for several months to assess effectiveness and tolerability before considering escalation to higher doses like 7.5mg or 10mg.
What are the common side effects at 5mg Mounjaro?
At the 5mg dose, the most common side effects are nausea, diarrhoea, constipation, and stomach pain. These often reduce over time as your body adapts. Less common side effects include vomiting, indigestion, fatigue, and injection site reactions. Always report persistent or severe symptoms to your prescriber — they can adjust your dose or provide management strategies.
Can I access 5mg Mounjaro privately in the UK?
Yes. Private GPhC-registered online pharmacies can dispense Mounjaro at any dose, including 5mg, following an online clinical assessment with a UK-licensed prescriber. Private costs vary by provider and dose, typically ranging from £129–£320 per month. This route doesn't require NHS referral or waiting lists, though the prescriber will still assess your suitability before issuing a prescription.
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.