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 Dose Levels in the UK
Mounjaro (tirzepatide) is available in six dose levels in the UK, starting at 2.5 mg and increasing to a maximum of 15 mg once weekly. Each dose is carefully adjusted over at least 4 weeks to find the right level for your individual health needs. Understanding how Mounjaro levels work, how they're prescribed through NHS specialist services or privately, and what to expect at each stage can help you make informed decisions about whether this prescription medication is right for you.
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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.
Mounjaro Dose Levels and NHS Eligibility in the UK
Mounjaro dose levels are administered as once-weekly injections using a KwikPen device. The standard dose titration schedule in the UK follows a structured 4-week escalation pattern:
- 2.5 mg — weeks 1–4 (starting dose for adjustment)
- 5 mg — weeks 5–8 (first maintenance level)
- 7.5 mg — weeks 9–12 (if escalation needed)
- 10 mg — weeks 13–16 (continued escalation)
- 12.5 mg — weeks 17–20 (further adjustment)
- 15 mg — week 21 onwards (maximum maintenance dose)
Not all patients require the maximum dose. Your prescriber will assess whether you should escalate based on your weight loss progress, side effects, and individual health factors. Clinical trials showed that patients on higher doses (10–15 mg) achieved average weight loss of approximately 19.5–20.9% of body weight over 72 weeks when combined with a reduced-calorie diet and increased physical activity. Access through NHS specialist tier 3 weight management services depends on your BMI and weight-related health conditions, though waiting times vary significantly by region.
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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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NHS vs Private Routes for Mounjaro in the UK
NHS access to Mounjaro is through specialist weight management services (tier 3 or tier 4), typically requiring a GP referral. NICE has approved tirzepatide for use within NHS weight management programmes, but availability varies by integrated care board (ICB), and some regions have substantial waiting lists. Private access is available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber — no NHS referral needed. Private costs typically range from £129–£320+ per month depending on your dose level. Use our free GLP-1 weight loss calculator above to explore how different Mounjaro dose levels might support weight loss projections alongside lifestyle changes. Your prescriber will determine which dose level is most appropriate for your individual circumstances.
- 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 standard starting dose is 2.5 mg once weekly for the first 4 weeks. This lower dose allows your body to adjust and helps identify any side effects early. After 4 weeks, your prescriber will typically increase you to 5 mg if tolerated, with further escalations every 4 weeks if needed.
Can I stay on a lower Mounjaro dose if it's working?
Yes. Not all patients need the maximum 15 mg dose. If you're achieving good weight loss and managing side effects well on a lower dose (such as 5 mg or 7.5 mg), your prescriber may recommend staying at that level rather than continuing to escalate.
How long does it take to reach the maximum Mounjaro dose?
Reaching 15 mg typically takes 20–21 weeks following the standard 4-week escalation schedule. However, your prescriber may adjust this timeline based on your progress and how you tolerate each dose level.
Is Mounjaro available on the NHS at all dose levels?
NICE has approved tirzepatide for NHS specialist weight management services, but access and dose availability vary by region. Some areas may have restrictions or waiting lists. Your NHS specialist service will determine which doses are available to you.
What's the difference between Mounjaro and Wegovy doses?
Mounjaro and Wegovy are different medications with different dose ranges. Mounjaro reaches a maximum of 15 mg, whilst Wegovy's maximum is 2.4 mg. They work through different mechanisms — Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy is a GLP-1 agonist only — so doses are not directly comparable.
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