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 2 Mounjaro: UK Cost and Access Guide
If you're starting Mounjaro in week 2, understanding how to access it in the UK is essential. Week 2 typically involves your second dose of 2.5 mg as you begin the titration process. Whether you're considering NHS access through specialist services or exploring private prescription options, this guide covers the actual costs, eligibility criteria, and what to expect. Our GLP-1 weight loss calculator can help you project potential outcomes at different Mounjaro doses as you progress through your treatment plan.
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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 Cost and Access Routes in the UK
Accessing tirzepatide (Mounjaro) in the UK depends on which route you choose: NHS or private. On the NHS, Mounjaro is available through specialist tier 3 weight management services following a GP referral. However, NHS availability varies significantly by region and integrated care board (ICB), with waiting lists often extending several months. Private prescription routes offer faster access without NHS referral, typically costing between £129 and £320 per month depending on dose and provider. At week 2, you're on the starting 2.5 mg dose, which is usually at the lower end of the cost range. Private access involves an online consultation with a UK-licensed prescriber who will assess your eligibility based on BMI and health conditions, then dispense through a GPhC-registered pharmacy. Your GP can advise on NHS availability in your area, whilst private options allow you to start immediately if clinically appropriate.
- NHS: Free once approved by specialist services (but long waiting lists)
- Private: £129–£180 typically for 2.5 mg dose per month
- Both routes require a prescription from a licensed prescriber
- Use our BMI calculator to check your eligibility based on current weight and height
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.
What Happens in Week 2 — Dose and Cost Considerations
Week 2 marks your second Mounjaro injection at the 2.5 mg starting dose. This is the adjustment phase, and you'll typically remain on this dose for weeks 1–4 before escalating. At this stage, side effects like nausea or stomach changes are common as your body adapts. The 2.5 mg dose is the most affordable on the private market, often costing £20–£35 per injection. Each KwikPen contains 4 doses (4 weeks supply), so your week 2 injection comes from your first pen. If you've chosen private access, your prescription will have been issued after your online consultation. If pursuing NHS access, week 2 may still be in the referral or assessment phase, depending on your local waiting time. Track your progress with our free progress tracker to monitor how you're responding as you complete the starting dose phase.
- 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 per month in the UK privately?
Private Mounjaro costs typically range from £129 to £320 per month depending on dose and provider. At week 2 (2.5 mg), expect to pay around £129–£180 monthly. Each KwikPen contains 4 weeks supply. Prices vary between online prescribing services, so it's worth comparing. Always verify the provider is GPhC-registered.
Can I get Mounjaro on the NHS for weight management?
Yes, Mounjaro is available on the NHS through specialist tier 3 weight management services. You'll need a GP referral. However, availability varies by region and waiting lists can be several months long. Contact your GP to check whether your local integrated care board offers Mounjaro through NHS services.
What's the difference between Mounjaro and Wegovy for cost and access?
Both require prescriptions and clinical assessment. Mounjaro (tirzepatide) and Wegovy (semaglutide) have similar private costs (£120–£320/month) but different dose ranges and mechanisms. Mounjaro is a dual GIP/GLP-1 agonist, whilst Wegovy is a GLP-1 agonist only. Compare outcomes using our GLP-1 weight loss calculator.
Do I need a referral to get Mounjaro privately?
No. Private Mounjaro access doesn't require an NHS referral. You simply complete an online consultation with a UK-licensed prescriber. If approved, they'll issue a prescription dispensed by a GPhC-registered pharmacy. This is faster than the NHS route but you pay privately.
What does the 2.5 mg Mounjaro KwikPen contain and how long does it last?
Each 2.5 mg KwikPen contains 4 pre-filled doses for 4 weeks of injections. Week 2 is your second injection from your first pen. You'll use one pen every 4 weeks at the 2.5 mg dose, then progress to higher doses (5 mg, 7.5 mg, etc.) if your prescriber recommends escalation after week 4.
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.