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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2.5 Mg Mounjaro In Ml — UK Dosing & Access
The 2.5 mg starting dose of Mounjaro (tirzepatide) is supplied in a pre-filled KwikPen, but the volume in millilitres varies depending on the specific formulation. Understanding how Mounjaro works, what it costs in the UK, and how to access it are crucial first steps if you're considering this prescription weight management medication. MyWeightCheck's free GLP-1 weight loss calculator can help you explore potential outcomes at different doses alongside lifestyle changes.
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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, Volume, And UK Prescription Access
Mounjaro is supplied as a pre-filled KwikPen injectable device, not as loose millilitres. Each pen contains 4 doses (4 weeks' supply) of a single strength. The 2.5 mg starting dose is the initial adjustment dose — patients typically remain on this for 4 weeks before escalating. Each KwikPen is calibrated to deliver the exact dose, so counting millilitres isn't necessary for users — the device automatically measures the correct volume.
- Each KwikPen contains 4 injections of the same dose
- 2.5 mg is the starting/adjustment dose only — not a maintenance dose
- Doses escalate every 4 weeks: 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg
- Clinical trials showed average weight loss of 15–21% body weight at higher maintenance doses
- Mounjaro is available through NHS specialist tier 3 services or private prescription in the UK
If you're considering Mounjaro, use our free BMI calculator above to establish your current health category, then discuss eligibility with your GP or a licensed prescriber.
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.
UK Cost, Access Routes, And What To Expect
Private prescription route: Mounjaro is available through licensed UK online prescribers following a clinical assessment, typically costing £129–£320 per month depending on dose. The 2.5 mg starting dose is usually at the lower end of this range. NHS route: Available through specialist weight management services for adults with BMI ≥30 or BMI ≥27.5 with weight-related conditions (South Asian, Chinese, Black African, Black Caribbean populations). NHS access varies significantly by region; many areas have waiting lists. An online consultation involves health questionnaires, past medical history, current medications, and contraindication screening. A prescriber assesses whether tirzepatide is suitable, then issues a prescription if appropriate.
- 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 exactly is the 2.5 mg Mounjaro dose in millilitres?
Mounjaro 2.5 mg is supplied in a pre-filled KwikPen — the exact millilitre volume depends on the formulation, but users don't need to measure it. The device automatically delivers the correct dose. Each pen contains 4 injections ready to use over 4 weeks.
How much does 2.5 mg Mounjaro cost in the UK?
Private prescription costs typically range from £129–£180 for a single 2.5 mg KwikPen (4 weeks' supply) through UK online prescribing services. NHS access is free but requires referral to specialist services and eligibility assessment. Costs vary by provider and region.
Can I get Mounjaro 2.5 mg on the NHS?
Yes, Mounjaro (tirzepatide) is approved by NICE for NHS specialist weight management services. You'll need referral from your GP to tier 3 services, a clinical assessment, and eligibility confirmation (BMI ≥30 or ≥27.5 with comorbidities). Availability and waiting times vary significantly by region.
How long do I stay on the 2.5 mg starting dose?
The 2.5 mg dose is the initial adjustment phase only — typically 4 weeks. After 4 weeks, your prescriber will usually increase you to 5 mg, then continue escalating every 4 weeks up to your maintenance dose, usually 10 mg or higher.
Is Mounjaro the same as Wegovy?
No. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Both are once-weekly injections licensed for weight management in the UK, but they work differently and have different dosing schedules. Clinical trials showed similar average weight loss outcomes, though individual results vary.
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.