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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Understanding Mounjaro Mg Doses in the UK
Mounjaro (tirzepatide) is available in the UK in doses ranging from 2.5 mg to 15 mg, administered once weekly by injection using a KwikPen device. This guide explains how Mounjaro dosing works under NHS guidance and private prescribing, the dose escalation schedule, and what you need to know about starting and maintaining treatment. Doses are tailored individually based on your response and tolerance.
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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 Mg Doses Work in the UK
Mounjaro is a prescription-only, once-weekly injectable medicine containing tirzepatide. In the UK, it is licensed for weight management in adults with a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. The MHRA (Medicines and Healthcare products Regulatory Agency) has approved Mounjaro and assigns it Black Triangle (▼) status, meaning it requires additional monitoring.
Doses are provided in a pre-filled KwikPen and escalated gradually over weeks. Starting at 2.5 mg, you remain on each dose for a minimum of 4 weeks before your prescriber considers increasing to the next level. This slow titration helps your body adjust and allows your prescriber to assess how well the medication is working and whether side effects are manageable. Maximum dose is 15 mg once weekly.
- Weeks 1–4: 2.5 mg (starting dose)
- Weeks 5–8+: 5 mg
- Weeks 9–12+: 7.5 mg
- Weeks 13–16+: 10 mg
- Weeks 17–20+: 12.5 mg
- Week 21+: 15 mg (maximum)
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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.
Mounjaro Mg on the NHS vs Private Routes in the UK
NHS access to Mounjaro is through specialist tier 3 weight management services, not standard GP prescription. Your GP can refer you to your local ICB (Integrated Care Board) specialist service, but availability and waiting times vary significantly across the UK. Some regions have substantial waiting lists. When prescribed through the NHS, your dose and ongoing care are managed by the specialist team.
Private prescribing offers faster access without an NHS referral. Following an online clinical assessment with a UK-licensed prescriber, Mounjaro may be dispensed by a GPhC-registered pharmacy. Whether you choose the NHS or private route, a qualified prescriber will assess your individual eligibility based on your BMI, health conditions, and medical history before determining your starting dose and escalation plan.
- 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 starting dose of Mounjaro in the UK?
The starting dose of Mounjaro in the UK is 2.5 mg once weekly. You remain on this dose for a minimum of 4 weeks before your prescriber considers increasing to 5 mg. This slow escalation allows your body to adjust and helps your prescriber monitor your response and tolerance.
How quickly can I increase my Mounjaro mg dose?
Each Mounjaro dose increase takes a minimum of 4 weeks. You must remain on your current dose for at least 4 weeks before escalating. Your prescriber will assess your response and any side effects before recommending an increase to the next dose level.
What is the maximum Mounjaro dose available in the UK?
The maximum licensed dose of Mounjaro in the UK is 15 mg once weekly. Not everyone needs to reach the maximum dose—your prescriber will determine the most effective and tolerable dose for you based on your individual response.
Is Mounjaro available through the NHS in the UK?
Yes, Mounjaro is available through NHS specialist tier 3 weight management services following GP referral. However, availability and waiting times vary by region. Private prescribing offers faster access without NHS referral, subject to clinical assessment.
How does Mounjaro compare to Wegovy in terms of dosing?
Mounjaro and Wegovy are different medications with different dose ranges. Mounjaro is a dual GIP/GLP-1 agonist (2.5–15 mg weekly), whilst Wegovy is a GLP-1 agonist only (0.25–2.4 mg weekly). Your prescriber will recommend the most appropriate option based on your health profile.
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.