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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What Does Monjaro Do — Understanding Cost and Access in the UK
Monjaro (tirzepatide) is a prescription-only weekly injection that works as a dual GIP and GLP-1 receptor agonist to support weight management. It helps reduce appetite and food cravings, making it easier to stick to a reduced-calorie diet. This guide explains how Monjaro works, what it costs in the UK, and how to access it through the NHS or privately. Understanding your options is the first step towards informed weight management decisions.
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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.
How Monjaro Works and What It Costs in the UK
Monjaro (tirzepatide) is a once-weekly weight loss injection that activates two natural hormone pathways: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). This dual action helps regulate appetite, increase feelings of fullness, and slow gastric emptying, making meals more satisfying.
- Starting dose: 2.5 mg weekly, escalating up to 15 mg maximum
- Clinical trials showed average weight loss of 15–21% of body weight on the highest dose
- Individual results vary significantly and depend on diet, exercise, and adherence
- Prescribed as a pre-filled KwikPen device — easy self-injection at home
UK private prescription costs typically range from £129 to £320 per month depending on dose and provider, with lower doses (2.5–5 mg) at the lower end and higher doses (10–15 mg) at the upper end. Costs do not include GP consultation or pharmacy dispensing fees, which vary.
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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.
Accessing Monjaro: NHS vs Private Routes
NHS access: Available through specialist tier 3/4 weight management services following GP referral. NICE has approved tirzepatide for NHS use, but availability varies significantly by region and waiting lists can extend several months. You'll need a BMI of 30 or above, or 27–29.9 with weight-related health conditions (lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults).
Private access: Prescription issued after a clinical assessment by a UK-licensed prescriber via online consultation — no NHS referral needed. The entire process typically takes 1–5 business days. You'll need to be assessed as clinically suitable, then pay for the prescription and medication directly. Use our free GLP-1 weight loss calculator to estimate potential results before consulting.
- 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 long does it take to get Monjaro on the NHS?
NHS access depends on your local integrated care board (ICB) and demand. Many areas have waiting lists of 3–12 months for specialist weight management services. Availability varies significantly across the UK. Contact your GP to check local waiting times and eligibility criteria in your area.
What's included in the private cost of Monjaro?
Private costs (£129–£320/month) typically cover the medication only. You'll usually pay separately for the online GP consultation (£20–£50), pharmacy dispensing, and any postage. Check with your chosen provider for an exact breakdown before purchasing.
Can I get Monjaro on prescription from my regular GP?
Not typically. GPs can initiate enquiries, but Monjaro is usually prescribed only through specialist tier 3/4 weight management services on the NHS. Private prescribers licensed in the UK can issue prescriptions after an online assessment without NHS referral.
Is Monjaro the same as the tirzepatide available privately?
Yes. Monjaro is the brand name for tirzepatide. Both NHS and private prescriptions are the same medication, manufactured by Eli Lilly. The difference is access route, waiting time, and who prescribes it—not the drug itself.
What happens after I get my Monjaro prescription?
Your prescription is sent to a GPhC-registered pharmacy, which dispenses the KwikPen device and ships it to you (usually within 2–5 business days). You'll receive storage instructions (refrigerate unopened; room temperature for 30 days after first use) and guidance on self-injection technique. Your prescriber should provide follow-up support.
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.