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
Week 3 Mounjaro: UK Access and Cost Guide
By week 3 of starting Mounjaro, you're still on the starter dose (2.5 mg), which is part of the standard dose titration schedule. Understanding the cost of accessing Mounjaro in the UK and your options—whether through the NHS or private prescription—is important before committing to treatment. This guide covers UK pricing, eligibility, and what to expect at this stage of your treatment journey.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Private Prescription Costs and UK Access Routes
In the UK, accessing Mounjaro (tirzepatide) involves two main routes: NHS specialist services or private prescription.
Private prescription costs for Mounjaro typically range from £150–£300+ per month depending on your dose and the prescriber. At week 3 you're on the 2.5 mg starter dose, which is usually at the lower end of the cost range. Each KwikPen contains 4 weekly injections, so costs are usually quoted per pen or per month. Private prescriptions require an online consultation with a UK-licensed prescriber, who will assess your eligibility based on BMI and health conditions. Once approved, your prescription is dispensed by a GPhC-registered pharmacy.
NHS access is significantly cheaper or free at point of use, but availability is limited. You must be referred to a tier 3 specialist weight management service by your GP, and waiting lists can extend months or years depending on your region. NICE has approved tirzepatide for NHS use, but funding decisions vary by Integrated Care Board (ICB).
Try our GLP-1 weight loss calculator to estimate potential outcomes at your current dose, which can help justify the investment to yourself or your 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.
NHS vs Private: Timeline, Cost, and What to Expect
NHS route: Referral from your GP to specialist services (weeks to months wait), then assessment and prescription if eligible. Free or minimal cost. Access depends on regional ICB funding and service capacity.
Private route: Online consultation with a licensed prescriber (typically 24–48 hours), assessment, and prescription issued if approved. Costs approximately £150–£300/month depending on dose. No waiting list, immediate access once prescription approved. You'll need to arrange ongoing consultations for dose adjustments or monitoring.
At week 3, you're still adjusting to the starter dose. Both routes allow dose escalation every 4 weeks if tolerated. Use our BMI calculator to confirm your eligibility before pursuing either route.
- 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 privately in the UK per month?
Private Mounjaro costs typically range from £150–£300+ per month depending on your dose and prescriber. At week 3 you're on 2.5 mg (the starter dose), which is usually at the lower end. Each KwikPen provides 4 weekly doses. Prices vary between providers, so compare before committing.
Can I get Mounjaro free on the NHS in week 3?
Yes, Mounjaro is available on the NHS through tier 3 specialist weight management services if you're eligible. However, access is limited and waiting lists are often very long—sometimes 6–12 months or more depending on your region. Your GP can refer you, but availability depends on your local ICB.
Do I need a private prescription for Mounjaro in the UK?
Yes, Mounjaro is prescription-only in the UK. You can obtain a prescription through the NHS (via specialist referral) or privately (via online consultation with a licensed prescriber). Either way, you need a valid prescription from a UK-licensed doctor to dispense it.
What's included in the cost of private Mounjaro treatment?
Private prescription costs usually cover the medication and the prescriber consultation. Ongoing monitoring, dose adjustments, and follow-up consultations may involve additional fees depending on the provider. Check what's included before you start—some services offer bundled packages.
Can I switch from private to NHS Mounjaro later?
It's theoretically possible but complicated. You'd need to stop private treatment and go through NHS referral and assessment again. Your GP may refer you based on your private treatment history, but it's not automatic. Discuss transition options with your GP if you're considering this.
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.