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 Is a Mounjaro Starter Bundle and How Much Does It Cost?
A Mounjaro starter bundle is the initial prescription package you receive when starting tirzepatide treatment in the UK. It typically includes four pre-filled KwikPen devices (a four-week supply at your starting dose) and usually costs between £129 and £180 depending on your dose and which private provider you use. Access in the UK is available through NHS specialist weight management services or private online prescribing following a clinical assessment. This guide explains your options, costs, and what to expect when beginning Mounjaro 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.
Understanding Mounjaro Starter Bundle Costs in the UK
A Mounjaro starter bundle provides four pre-filled KwikPen devices — enough for four weekly injections at your starting dose. Private prescription costs vary by provider and dose:
- 2.5 mg (starting dose): approximately £129–£145 per bundle
- 5 mg (first escalation): approximately £145–£165 per bundle
- Higher doses (7.5 mg+): approximately £165–£180 per bundle
Each bundle lasts four weeks. Most patients remain on their starting dose for at least four weeks before dose titration occurs, meaning a typical first month costs £129–£145. NHS access is free at point of care but involves referral to a tier 3 specialist weight management service, which varies significantly by region and may involve waiting lists. Private online prescribing offers faster access without NHS referral but requires payment upfront. Costs are per bundle rather than per injection, making it straightforward to budget for ongoing treatment.
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: How to Access Mounjaro in the UK
NHS route: Referral from your GP to your local integrated care board (ICB) tier 3 weight management service. Free at point of care, but regional availability varies significantly and waiting times can be several months in some areas. NICE has approved tirzepatide for NHS use within specialist services. Private route: Online consultation with a UK-licensed prescriber, clinical assessment, and prescription issued if appropriate. Dispensed by a GPhC-registered pharmacy. No NHS referral needed — you can start within days of your consultation. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses, helping you understand whether this investment aligns with your goals. Private treatment is your responsibility, but access is faster and more predictable than NHS waiting lists.
- 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 comes in a Mounjaro starter bundle?
A starter bundle contains four pre-filled KwikPen devices at your starting dose (usually 2.5 mg), providing a four-week supply of once-weekly injections. Each pen is single-use and pre-filled. You also receive injection guidance and storage instructions with your prescription.
Can I get a Mounjaro starter bundle on the NHS?
Yes, through NHS tier 3 specialist weight management services following referral from your GP. It's free at point of care, but availability and waiting times vary significantly by region. Private access is often faster if you're willing to pay privately.
How long does a starter bundle last?
Four weeks. You inject once per week for four weeks, then move to your next bundle — which may be the same dose or an escalated dose depending on your prescriber's guidance and how you've responded.
Do I need a clinical assessment before getting a starter bundle?
Yes. Whether through NHS or private prescribing, a licensed prescriber must assess your eligibility based on your BMI, health conditions, current medications, and medical history. Use our BMI calculator to check your starting point before your consultation.
What's the difference between Mounjaro and Wegovy starter bundles?
Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist; Wegovy (semaglutide) is GLP-1 only. Mounjaro starter bundles begin at 2.5 mg; Wegovy begins at 0.25 mg. Clinical trials showed Mounjaro produced slightly higher average weight loss, but individual results vary significantly. Both require prescription and clinical assessment.
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.