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 Golden Dose: How to Use and Access in the UK
The "golden dose" of Mounjaro refers to the 15 mg maintenance dose—the maximum weekly injection that clinical trials showed delivers optimal weight loss results. Understanding how to use your Mounjaro KwikPen correctly, along with UK access routes and costs, is essential for anyone considering this prescription weight loss treatment. Whether you're exploring NHS options or private prescription routes, this guide explains how Mounjaro works, the titration schedule that leads to the golden dose, and what you can realistically expect. Use our free GLP-1 weight loss calculator above to estimate your potential outcomes at different doses.
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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.
UK Prescription Routes, Costs & How to Use Your KwikPen
Mounjaro (tirzepatide) is a prescription-only medicine available in the UK through NHS specialist weight management services or private online prescription services. On the NHS, access requires referral to a tier 3 specialist service through your GP—waiting times vary significantly by region, often ranging from several months to over a year. Private prescription costs typically range from £129–£320 per month depending on the dose and provider. Your KwikPen contains four pre-filled doses (one month's supply) and is injected once weekly into your stomach, thigh, or upper arm. The golden dose of 15 mg—reached after a gradual 20-week titration schedule starting at 2.5 mg—showed average weight loss of approximately 21% body weight in clinical trials, though individual results vary considerably. Before accessing Mounjaro through either route, a licensed prescriber must assess your eligibility, medical history, and any contraindications. Mounjaro vs Wegovy comparisons show similar weight loss outcomes, though tirzepatide's dual GIP and GLP-1 mechanism differs from semaglutide's single GLP-1 pathway.
- NHS route: Free at point of use but requires specialist referral and assessment
- Private route: Faster access (typically within days) following an online consultation with a UK-licensed prescriber
- KwikPen storage: Unopened pens in fridge at 2–8°C; after first use, room temperature (below 30°C) for up to 30 days
- Dose frequency: One injection per week, same day each week for consistency
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.
Getting Started: Mounjaro UK Prescription & What to Expect
Getting a Mounjaro prescription in the UK starts with either a GP referral to NHS specialist services or an online consultation with a GPhC-registered prescriber via a private clinic. The private route involves completing a health questionnaire, online video call assessment, and prescription issuance if approved—this typically takes 24–48 hours. You'll receive detailed instructions on injection technique, storage, and dose schedule. Mounjaro dose titration begins at 2.5 mg weekly for four weeks, escalating every four weeks to 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally the golden dose of 15 mg. Side effects UK patients commonly report include nausea, diarrhoea, and stomach pain—usually mild and diminishing over time. Monitor your progress using our free weight loss calculator and progress tracker to log results week by week.
- Initial consultation assesses medical history, medications, and weight-related health conditions
- Four-week minimum at each dose ensures your body adapts before escalation
- Eligibility UK criteria: BMI ≥30, or ≥27 with weight-related health conditions like type 2 diabetes or high blood pressure
- 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 golden dose and why is it called that?
The golden dose of 15 mg is Mounjaro's maximum weekly dose, shown in SURMOUNT clinical trials to deliver the highest average weight loss (approximately 21% body weight). It's termed "golden" because it represents the optimal therapeutic dose where benefits plateau—higher doses aren't available or clinically beneficial.
How long does it take to reach the 15 mg golden dose?
The titration schedule takes approximately 20 weeks. You start at 2.5 mg, then increase by one dose level every four weeks: 5 mg (week 5), 7.5 mg (week 9), 10 mg (week 13), 12.5 mg (week 17), reaching 15 mg by week 21. Your prescriber may adjust this based on side effects.
How much does Mounjaro cost privately in the UK?
Private Mounjaro costs range from approximately £129–£320 per month depending on the dose. Lower doses (2.5–5 mg) are typically cheaper; the golden dose (15 mg) is at the higher end. Each KwikPen contains four weekly injections. NHS prescriptions are free but require specialist referral.
Can I access Mounjaro on the NHS in the UK?
Yes, but it requires referral to a NHS tier 3 specialist weight management service. NICE has approved tirzepatide for NHS use, though availability varies by region and waiting lists can be lengthy. Your GP can refer you if you meet eligibility criteria (BMI ≥30 or ≥27 with weight-related health conditions).
What are the most common side effects when starting Mounjaro?
Very common side effects include nausea, diarrhoea, constipation, vomiting, and stomach pain. These typically occur in the first few weeks and often improve as your body adjusts. Starting at the low 2.5 mg dose and slow titration help minimise severity. Contact your GP if side effects persist or worsen.
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.