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
Free tracker included with every download this week
What Mounjaro Doses Are Available in the UK?
Mounjaro (tirzepatide) comes in six different doses, starting at 2.5 mg and increasing gradually to a maximum of 15 mg once weekly. The UK prescription pathway offers two routes: NHS specialist services or private prescribing following an online clinical assessment. Understanding the dosing schedule, cost implications, and eligibility criteria helps you decide which route suits your situation. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses based on clinical trial data.
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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 Dosing Schedule and What to Expect
Mounjaro is prescribed as a progressive dose titration, meaning you start low and increase gradually over several weeks. Each dose is administered as a once-weekly KwikPen injection:
- Weeks 1–4: 2.5 mg (starting dose)
- Weeks 5–8: 5 mg (first increase)
- Weeks 9–12: 7.5 mg
- Weeks 13–16: 10 mg
- Weeks 17–20: 12.5 mg
- Week 21+: 15 mg (maximum maintenance dose)
You must stay on each dose for a minimum of 4 weeks before increasing. Clinical trials showed that at 15 mg (the maximum dose), people lost an average of approximately 21% of their body weight over 72 weeks, though individual results vary significantly. Your prescriber will assess whether you need to progress through all doses or stabilise at a lower dose if you're achieving good results.
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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.
Mounjaro Cost in the UK: NHS vs Private Access
NHS route: If prescribed through an NHS specialist weight management service, Mounjaro is typically provided free. However, access depends on regional availability and specialist tier 3/4 services, with waiting lists often extending several months. Your GP can refer you, but not all ICBs (Integrated Care Boards) currently commission this treatment.
Private route: Through GPhC-registered online pharmacies following a clinical consultation with a UK-licensed prescriber, Mounjaro costs vary by dose but typically range from £129–£320 per month depending on your starting dose and which private provider you use. Each KwikPen contains 4 weekly doses. Private access is immediate once assessed and approved — no NHS referral needed.
- 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.
How much does Mounjaro cost on prescription in the UK?
Private prescriptions range from approximately £129–£320 per month depending on dose. Through NHS specialist services, it's free if eligible, but availability varies by region and waiting lists can be lengthy. Online pharmacies offer different pricing tiers.
Can my GP prescribe Mounjaro directly?
Most GPs cannot prescribe Mounjaro for weight management on the NHS. It's typically prescribed through NHS specialist tier 3 weight management services. Private prescriptions can be issued by UK-licensed prescribers following an online assessment.
What's the difference between Mounjaro and Wegovy doses?
Mounjaro starts at 2.5 mg and increases to 15 mg maximum. Wegovy starts at 0.25 mg and increases to 2.4 mg maximum. They're different medications with different dosing schedules. Mounjaro is a dual GIP/GLP-1 agonist, while Wegovy is a GLP-1 agonist only. Approximate equivalence: Mounjaro 5 mg ≈ Wegovy 0.5 mg.
Do I need to go through all dose increases?
No. Your prescriber will assess your progress at each dose. If you're achieving good weight loss and tolerating the medication well, you may stabilise at a lower dose rather than continuing to the maximum 15 mg.
How long do I stay on each Mounjaro dose?
A minimum of 4 weeks on each dose before increasing, with a typical schedule moving to the next dose at week 4. However, if you experience side effects, your prescriber may extend the time at a lower dose or reduce the dose to manage symptoms better.
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.