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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How Do I Get Mounjaro in the UK?
Getting Mounjaro in the UK involves two main routes: NHS specialist services or private online prescribing. Mounjaro (tirzepatide) is a prescription-only weight management injection, so you'll need a clinical assessment before it can be prescribed. This guide explains both pathways, eligibility criteria, and what happens after prescription. The route you choose depends on your circumstances, waiting time tolerance, and budget.
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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.
Two Routes to Access Mounjaro in the UK
NHS Route: Mounjaro is available through NHS specialist weight management services (tier 3). You'll need a referral from your GP to your local Integrated Care Board (ICB) weight management service. NICE has approved tirzepatide for NHS use, but availability and waiting times vary significantly by region—some areas have waiting lists of several months or longer. Your GP will assess whether specialist referral is appropriate and can discuss any weight-related health conditions with you.
Private Route: You can access Mounjaro through private online prescribing without an NHS referral. This involves an online consultation with a UK-licensed prescriber, who will assess your eligibility based on BMI and health history. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy. This route typically offers faster access but involves private costs, ranging from approximately £129 to £320 per month depending on your dose and provider.
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.
Eligibility and What Happens Next
To be eligible for Mounjaro in the UK, you must have a BMI of 30 kg/m² or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Lower thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage. Once prescribed, your GP or the prescribing service will provide injection training and ongoing support. You'll receive Mounjaro as a KwikPen (pre-filled injection device) and will start on 2.5 mg, increasing by 2.5 mg every 4 weeks up to your target dose. Use our GLP-1 weight loss calculator to estimate potential results at different doses.
After starting Mounjaro, you'll monitor for side effects—common ones include nausea, which often improves within a few weeks. Your prescriber will review your progress at regular intervals. If you're on other medications, particularly oral contraceptives or diabetes medication, inform your prescriber as Mounjaro may affect absorption. Keep your injection pens refrigerated if unopened, or at room temperature for up to 30 days after first use. Track your progress using our free progress tracker to monitor weight changes alongside your dose increases.
- 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 Mounjaro on the NHS?
NHS waiting times vary by region from 2–12 months or longer. Your local ICB determines availability and speed. Private access typically takes 1–2 weeks from online consultation to first delivery.
Do I need a GP referral to get Mounjaro privately?
No. Private online prescribing doesn't require an NHS referral. You can access private prescribing directly by completing an online consultation with a UK-licensed prescriber.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP+GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials suggest Mounjaro may result in slightly higher average weight loss (~15–21% vs ~15% body weight). Both are prescription-only and require clinical assessment.
What if I don't meet the BMI threshold for Mounjaro?
If your BMI is 27–29.9, you may still be eligible if you have weight-related health conditions such as type 2 diabetes, hypertension, or sleep apnoea. Discuss this with your GP or the assessing prescriber, as individual circumstances vary.
Can my GP prescribe Mounjaro directly?
GPs cannot routinely prescribe Mounjaro on the NHS—it must come through specialist tier 3 weight management services. Some private GPs may prescribe privately, but most Mounjaro prescriptions come through online prescribing services or NHS specialist clinics.
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.