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 Weight Loss Dosage in the UK
Mounjaro (tirzepatide) is available on prescription in the UK for adults eligible for weight management treatment, with doses ranging from 2.5mg to 15mg once weekly. The medication is administered as a once-weekly injection via a pre-filled KwikPen device. NHS access is through specialist tier 3 weight management services following NICE guidance, though private prescribing is also available. Understanding how dosages work and the titration schedule helps you know what to expect if prescribed this weekly weight loss injection. Use our free GLP-1 weight loss calculator to explore potential results at different doses, and our BMI calculator to check your starting point.
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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.
Mounjaro Dosage Schedule and NHS Eligibility
Mounjaro comes in five standard doses, with treatment beginning at the lowest dose and increasing gradually every four weeks if tolerated:
- 2.5mg — weeks 1–4 (starting/adjustment dose)
- 5mg — weeks 5–8 (first maintenance)
- 7.5mg — weeks 9–12 (escalation if needed)
- 10mg — weeks 13–16 (further escalation)
- 12.5mg — weeks 17–20 (optional escalation)
- 15mg — week 21 onwards (maximum dose)
NHS prescribing via NICE guidance covers adults with a BMI of 30kg/m² or above, or 27–29.9kg/m² with at least one weight-related health condition (type 2 diabetes, hypertension, dyslipidaemia, sleep apnoea, or cardiovascular disease). For adults of South Asian, Chinese, Black African, or Black Caribbean backgrounds, lower BMI thresholds may apply (BMI 27.5 or above). Eligibility is assessed through specialist tier 3 weight management services, typically following a GP referral.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 vs Private Mounjaro Access in the UK
In the UK, Mounjaro is prescription-only and accessed through two main routes. NHS access is via specialist weight management services (tier 3) — availability varies significantly by region and integrated care board (ICB), with some areas offering faster access than others. Private access is through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber — this route does not require NHS referral and may be faster, though costs apply. Both routes require the prescriber to assess whether tirzepatide is clinically appropriate based on your individual health, medical history, and any contraindications. Whichever route you choose, Mounjaro works best alongside a reduced-calorie diet and increased physical activity — the medication alone is not a standalone solution.
- 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 dose of Mounjaro is most effective for weight loss?
Clinical trials showed that higher doses (10–15mg weekly) typically produced greater average weight loss than lower doses. In the SURMOUNT-1 trial, participants on 15mg lost approximately 20.9% of body weight over 72 weeks. However, individual results vary significantly, and the most effective dose for you depends on tolerability and personal response. Your prescriber will titrate your dose gradually to find the right balance.
How long does it take to increase Mounjaro doses?
The NHS and clinical guidance recommend a minimum of four weeks on each dose before increasing to the next level. This allows your body to adjust and helps your prescriber assess tolerability and effectiveness. If you experience significant side effects, you may stay on a particular dose longer or your prescriber may recommend a slower escalation.
Can I stop at a lower Mounjaro dose if it's working?
Yes. You do not need to reach the maximum 15mg dose. If you are experiencing good weight loss results and tolerating side effects well at a lower dose (such as 7.5mg or 10mg), your prescriber may recommend maintaining that dose rather than continuing to escalate. The goal is to find the dose that works best for your individual situation.
Is Mounjaro available on the NHS in all UK regions?
NHS availability varies by region. NICE has approved tirzepatide for use in NHS specialist weight management services, but access depends on your local integrated care board (ICB) and tier 3 service capacity. Waiting lists and eligibility criteria can differ. Your GP can refer you to local services, or you can enquire directly with your local NHS weight management service.
What's the difference between the Mounjaro dose for weight loss and diabetes?
Mounjaro at 15mg weekly is the maximum approved dose for weight management in the UK. The diabetes-approved formulation (Mounjaro for type 2 diabetes) also uses the same 2.5–15mg range. However, dosing schedules and clinical monitoring may differ between weight management and diabetes use — always follow your prescriber's instructions for your specific indication.
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.