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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Mounjaro 5th Dose in Pen: UK Cost and Access
Mounjaro comes in pre-filled KwikPen devices, with each pen containing four weekly doses. If you're on your fifth dose, you're moving into the dose escalation phase of your treatment. This guide explains what the 5th dose means for your Mounjaro journey, how much it costs in the UK, and how to access tirzepatide through NHS specialist services or private prescription routes. Whether you're considering treatment or already receiving injections, understanding your costs and options is essential for managing your weight loss plan effectively.
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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 Schedule and the 5th Dose
The 5th dose of Mounjaro falls in week 5 of treatment, where most people remain on the 2.5 mg starting dose before their prescriber considers an escalation. However, depending on individual response and clinical guidance, some patients may be escalated to 5 mg at this point. Each Mounjaro KwikPen contains exactly four pre-filled doses, so reaching your 5th dose means you'll need a second pen.
- Weeks 1–4: 2.5 mg (first pen)
- Week 5 onwards: 5 mg or remaining on 2.5 mg (second pen begins)
- Minimum 4 weeks at each dose before escalation
- Maximum dose: 15 mg once weekly
- Prescribers assess tolerability before increasing tirzepatide doses
Your GP or prescriber will review your progress, side effects, and weight loss before deciding whether to escalate. If tolerating the 2.5 mg well, you may remain on it for longer. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses.
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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
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Mounjaro Cost in the UK: NHS vs Private Access
NHS access: Mounjaro is approved by NICE for NHS specialist weight management services, but availability is limited and regional variation is significant. Waiting lists can be lengthy, and access depends on meeting strict eligibility criteria and ICB funding decisions. No direct cost to you if prescribed through the NHS.
Private access: Available through UK-licensed prescribers via online consultation. Costs typically range from £129–£320 per month depending on dose. A private prescription allows your pharmacist to dispense Mounjaro once a UK prescriber has assessed your suitability. Costs may be higher for higher doses like the 5 mg escalation point. Private options offer faster access without NHS waiting lists but require out-of-pocket payment.
- 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 dose in the UK?
Private Mounjaro typically costs between £129–£320 per month depending on your dose. A single KwikPen contains four doses (one month's supply). Exact pricing varies by pharmacy and dose. The 5th dose would be part of your second pen. NHS access is free but availability is limited and regional. Check your GLP-1 weight loss calculator projection to understand potential outcomes.
What happens at the 5th Mounjaro dose?
Your 5th dose (week 5) signals the end of your first KwikPen and the start of your second pen. Most people remain on 2.5 mg initially, though some may escalate to 5 mg if tolerating treatment well. Your prescriber reviews side effects and weight loss progress before deciding on dose escalation. Minimum time on each dose is four weeks.
Can I access Mounjaro through the NHS for the 5th dose onwards?
Yes, if already prescribed through an NHS specialist weight management service, you'll continue through the NHS with no additional cost. However, initial NHS access involves waiting for a tier 3 specialist service referral and assessment. Regional availability varies significantly. Private prescription is faster but requires payment per pen.
What's the difference between Mounjaro and Wegovy in terms of dosing?
Mounjaro (tirzepatide) starts at 2.5 mg and escalates to a maximum of 15 mg weekly. Wegovy (semaglutide) starts at 0.25 mg and escalates to 2.4 mg weekly. Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy is GLP-1 only. Both require minimum four weeks at each dose before escalation. Clinical trials showed different average weight loss outcomes.
Do I need a prescription for each Mounjaro pen, or just the first one?
You need a valid prescription from a UK-licensed prescriber for each pen supply. Some prescribers issue prescriptions for multiple pens upfront (e.g. three-month supply), while others issue one at a time. Always ensure your prescriber has assessed your ongoing suitability before refilling. Both NHS and private routes require valid prescriptions.
Ready to take control of your weight loss journey?
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