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 Highest Dosage: UK Cost and Access
Mounjaro's highest dosage is 15mg, administered once weekly as a pre-filled KwikPen injection. However, most people start at 2.5mg and gradually increase over several months, reaching the maximum dose only if needed and tolerated. This guide explains the 15mg dose, eligibility requirements, UK pricing, and how to access Mounjaro through both NHS specialist services and private prescription routes. Use our free BMI calculator to check your starting point, and our GLP-1 weight loss calculator to explore potential outcomes at different dose levels.
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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 15mg: Dosage, Escalation, and What It Costs in the UK
Mounjaro 15mg is the maximum approved dose in the UK. It is prescribed as a once-weekly injection using a pre-filled KwikPen device. Reaching 15mg requires a structured dose titration schedule — most patients start at 2.5mg and escalate every 4 weeks: 2.5mg (weeks 1–4), 5mg (weeks 5–8), 7.5mg (weeks 9–12), 10mg (weeks 13–16), 12.5mg (weeks 17–20), then 15mg (week 21 onwards).
Clinical trials using tirzepatide (the active ingredient in Mounjaro) showed that patients on the 15mg dose achieved an average weight loss of approximately 20.9% of their body weight over 72 weeks, alongside reduced-calorie diet and increased physical activity. However, individual results vary significantly — some patients experience meaningful weight loss at lower doses and do not escalate further.
Not everyone reaches 15mg. Your prescriber may keep you at 10mg or 12.5mg if that dose is delivering results and is well-tolerated. Side effects like nausea or constipation can influence dose escalation decisions.
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.
UK Costs and How to Access Mounjaro: NHS vs Private Routes
Private prescriptions cost between £150–£300 per month depending on the dose and pharmacy. A 15mg KwikPen (one month's supply) typically costs £250–£320 privately. Private access is through an online consultation with a UK-licensed prescriber — no NHS referral needed. The online assessment checks your medical history and eligibility, and if approved, your prescription is dispensed by a GPhC-registered pharmacy.
NHS access is through specialist tier 3 weight management services, accessed by GP referral. NICE has approved Mounjaro (tirzepatide) for NHS use, but availability and waiting times vary significantly by region. Some NHS areas have 12+ month waiting lists; others have faster access. Your GP can advise whether specialist services are available in your area and what the current waiting time is.
Online consultation process: You complete a health questionnaire online, a UK-licensed doctor reviews it, and if you meet eligibility criteria (BMI ≥27.5–30 with health conditions, or BMI ≥30), a prescription is issued. You then pay for the medication and it is dispatched. First prescriptions often require fortnightly doses to establish tolerance, then monthly. Use our progress tracker to log your weight and side effects as you escalate — this helps you and your prescriber decide if higher doses are right for you.
- 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 is Mounjaro's maximum dose and when is it prescribed?
Mounjaro's maximum approved dose is 15mg once weekly. It is only prescribed at this level if lower doses haven't delivered adequate results and it is well-tolerated. Most people escalate gradually — starting at 2.5mg and increasing every 4 weeks over 20+ weeks. Not all patients need or reach 15mg.
Does Mounjaro 15mg assures more weight loss than lower doses?
No. Clinical trials showed 15mg achieved approximately 20.9% average weight loss, but individual results vary widely. Some people lose similar amounts at 10mg or 12.5mg. Prescribers consider your response, side effects, and overall health when deciding whether to escalate to maximum dose.
How much does Mounjaro 15mg cost on private prescription in the UK?
A 15mg KwikPen (one month) typically costs £250–£320 on private prescription. Costs vary by pharmacy and whether you're starting titration or on a maintenance dose. Some online pharmacies offer bundled pricing for multiple months. Always check the final price with your pharmacy before paying.
Can I get Mounjaro 15mg on the NHS in the UK?
NICE has approved tirzepatide for NHS weight management, but access is through specialist tier 3 services via GP referral. Availability and waiting times vary by region — some areas have lengthy waiting lists. Your GP can check current access in your area and refer you if you meet criteria.
What happens if I cannot tolerate Mounjaro 15mg?
If higher doses cause significant side effects, your prescriber can reduce you to a lower maintenance dose (10mg or 12.5mg) where you experienced better tolerance. Dose adjustment is normal — the goal is effective weight management with side effects you can manage, not reaching maximum dose.
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.