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
2.5 Mg Mounjaro in Units — UK Cost and Access Guide
The 2.5 mg dose is Mounjaro's starting dose — the first step in the tirzepatide treatment journey for weight management in the UK. Understanding the cost and how to access this initial dose is essential before starting. Both NHS and private routes are available, though access, timelines, and costs differ significantly. This guide explains your options, what to expect during assessment, and how the dose titration process works once you begin treatment.
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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.
NHS vs Private Access — What's the Real Cost?
NHS access to Mounjaro is available through specialist tier 3 weight management services, but you'll need a referral from your GP. The medication itself is free once prescribed through the NHS, but access is limited by regional availability and waiting lists can extend many months in some areas. Your GP will assess whether you meet eligibility criteria: a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease.
Private access costs approximately £129–£160 per month for the 2.5 mg starter dose through UK-registered online pharmacies following an online clinical consultation. This includes the KwikPen (pre-filled injection pen with 4 weeks of doses) plus the prescriber assessment. Some providers bundle additional support like lifestyle coaching or progress tracking at higher cost tiers. The entire process — from consultation to receiving your first pen — typically takes 3–5 working days.
- NHS: Free medication, but referral and waiting list required
- Private: £129–£160/month, faster access (3–5 days), no referral needed
- Both routes require clinical assessment and prescription
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.
Getting Started — What Happens Next?
Once you've chosen your route, you'll have a clinical assessment to confirm Mounjaro is suitable for you. A prescriber will review your medical history, current medications, and whether you have any contraindications (such as pregnancy plans, personal or family history of medullary thyroid cancer, or severe gastroparesis). At 2.5 mg, you'll inject once weekly for 4 weeks — this is your titration period before the dose increases to 5 mg in week 5. You'll need to use our free GLP-1 weight loss calculator to estimate your potential progress and track your results using our progress tracker as you move through the dose escalation schedule. Most people experience nausea during the first few weeks, which typically improves as your body adjusts. Your prescriber will discuss side effects and when to seek medical help.
- 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 long do I stay on 2.5 mg Mounjaro before the dose increases?
You stay on 2.5 mg for exactly 4 weeks (weeks 1–4). In week 5, the dose increases to 5 mg, assuming no significant side effects. Each dose increase requires another 4-week minimum period. The full titration schedule to maximum dose (15 mg) takes approximately 20 weeks.
Can I get 2.5 mg Mounjaro on the NHS straight away?
Not immediately. You'll need a GP referral to a specialist tier 3 weight management service, and waiting lists vary widely by region — some areas have waiting times of 6–18 months. Once referred, the specialist will assess your eligibility. Private access is much faster (3–5 days).
What's included in the £129–£160 private cost for 2.5 mg Mounjaro?
The cost typically covers the online clinical assessment by a UK-licensed prescriber, the prescription itself, and the KwikPen device (which contains 4 weeks of 2.5 mg doses). Some providers include follow-up support or progress tracking; others charge separately. Always check what's included before ordering.
How does 2.5 mg Mounjaro differ from the same dose of Wegovy?
Mounjaro's 2.5 mg is a dual GIP and GLP-1 agonist, while Wegovy uses only GLP-1. Wegovy's starter dose is actually lower (0.25 mg), making direct dose comparison difficult. Mounjaro tends to show slightly stronger average weight loss in clinical trials, but individual results vary significantly. Your prescriber can advise which is more suitable for you.
Do I need to use our BMI calculator or weight converter before starting?
Yes — use our free BMI calculator to establish your baseline and confirm your eligibility (BMI 27 or above typically qualifies). Our weight converter helps you track progress in your preferred units (kg, stone, or lbs), and our progress tracker lets you log weekly weight changes throughout your treatment journey.
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.