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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5mg Mounjaro Pen — What You Need to Know in the UK
The 5mg dose of Mounjaro (tirzepatide) is typically the first maintenance dose in the UK weight management pathway. It's an important step in your treatment escalation, following the initial 2.5mg starting dose. Understanding how the 5mg dose works within NHS and private prescribing in the UK, its role in dose titration, and what clinical evidence tells us will help you make informed decisions with your prescriber. Use our GLP-1 weight loss calculator to see projected outcomes, and our BMI calculator to understand your current health status.
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.
NHS Access and 5mg Mounjaro Dosing in the UK
The 5mg dose is where most UK patients on Mounjaro remain for their initial maintenance period. In clinical trials, the 5mg dose was associated with approximately clinically studied weight loss on average — though individual results vary significantly. This dose is typically reached in week 5 of treatment, after 4 weeks on the starting 2.5mg dose. The Mounjaro KwikPen at 5mg is administered once weekly as a subcutaneous injection.
NHS eligibility for Mounjaro remains consistent across all doses: you must have a BMI of 30 kg/m² or above, or BMI of 27–29.9 kg/m² with weight-related conditions such as type 2 diabetes, hypertension, or sleep apnoea. For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds (27.5+) may apply. Access is through NHS specialist tier 3 weight management services, not routine GP prescription. Waiting lists vary significantly by region, and availability depends on your local Integrated Care Board (ICB) commissioning decisions.
- 5mg dose typically maintained for at least 4 weeks before escalation
- Average weight loss at 5mg: approximately 15% body weight
- Clinical trials (SURMOUNT) support 5mg as an effective maintenance dose
- Side effects (nausea, diarrhoea, constipation) often peak around weeks 2–4 then stabilise
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 Route for 5mg Mounjaro in the UK
NHS route: Prescribed through specialist weight management services following GP referral. You'll be assessed by a multidisciplinary team including nurses, dietitians, and doctors. Treatment is free at point of care, but waiting lists in many areas extend to 18+ months. Once prescribed, the 5mg dose and all escalations are provided by the NHS.
Private route: Prescribed following an online clinical consultation with a UK-licensed prescriber. Available without NHS referral, dispensed by GPhC-registered pharmacies. Faster access (usually within 1–2 weeks), but you pay for each dose — typically £129–£160 per month at 5mg. Both routes require the same clinical assessment criteria and provide the same medication.
Your GP can advise on local NHS availability. Track your progress with our free progress tracker once you begin treatment.
- 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 weight will I lose on 5mg Mounjaro?
Clinical trials showed an average weight loss of approximately 15% body weight at the 5mg dose. However, individual results vary significantly — some people lose more, others less. Weight loss depends on your starting weight, adherence to a reduced-calorie diet, physical activity, genetics, and other health factors. Your prescriber will monitor your progress and may adjust your dose if needed.
Is 5mg the maximum dose of Mounjaro in the UK?
No. 5mg is a maintenance dose, not the maximum. The Mounjaro dose escalation continues to 7.5mg, 10mg, 12.5mg, and finally 15mg — the maximum licensed dose in the UK. Most people remain on 5mg for several weeks before deciding whether to escalate. Your prescriber will discuss escalation based on your weight loss response and how well you tolerate the medication.
How do I get 5mg Mounjaro prescribed on the NHS in the UK?
You need referral from your GP to a specialist tier 3 weight management service in your area. These services are typically run by NHS trusts or integrated care boards. They will assess your eligibility (BMI 30+, or 27+ with weight-related conditions) and, if appropriate, initiate Mounjaro treatment. Waiting times vary by region — contact your local ICB for expected timescales.
What is the difference between 5mg Mounjaro and 5mg Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. The 5mg Mounjaro dose is not directly equivalent to a specific Wegovy dose — Wegovy's doses are lower (0.25mg to 2.4mg). Clinical trials suggest Mounjaro may produce greater weight loss than Wegovy at equivalent stages, but results vary between individuals.
Can I buy a 5mg Mounjaro pen without a prescription?
No. Mounjaro is prescription-only in the UK and requires a clinical assessment by a licensed prescriber before it can be dispensed. The prescriber must confirm you meet eligibility criteria (BMI, health conditions) and that the medication is safe for you based on your medical history and current medications.
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.