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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Getting Mounjaro Through Online Pharmacies in the UK
Mounjaro (tirzepatide) is a prescription-only weight management injection available in the UK through both NHS specialist services and private online prescribing routes. Understanding how to access it legally requires knowing the difference between NHS tier 3 services and private GPhC-registered online pharmacies. This guide explains UK eligibility criteria, NICE approval, and what to expect when seeking Mounjaro through either pathway. Calculate your BMI using our free tool above to check if you may be eligible for weight management support.
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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.
NHS Access vs Private Online Routes for Mounjaro
NHS Route: NICE approved tirzepatide (Mounjaro) in 2024 for use within specialist weight management services. Access requires referral to your local tier 3 or tier 4 weight management service through your GP. You must meet eligibility criteria: BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea, cardiovascular disease). For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds may apply (from 27.5). NHS waiting lists for specialist services vary significantly by region and can extend many months.
Private Online Route: Available through GPhC-registered online pharmacies without NHS referral. You complete an online clinical assessment with a UK-licensed prescriber who reviews your health history and decides whether tirzepatide is appropriate. If approved, a prescription is issued and dispensed by the pharmacy. This route is typically faster but involves private costs ranging from £130–£300 monthly depending on dose. Prescription must still be issued by a UK-licensed healthcare professional following proper clinical assessment.
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.
NICE Guidance, Eligibility, and What to Expect
NICE guidance specifies that tirzepatide may be prescribed within tier 3 specialist weight management services for adults with BMI 30+ (or 27+ with comorbidities). The Mounjaro KwikPen is a once-weekly injectable device; doses begin at 2.5 mg and titrate up to a maximum of 15 mg. Clinical trials (SURMOUNT-1) showed average weight loss of approximately 15–21% body weight alongside diet and physical activity changes. Any online pharmacy must verify your identity, assess medical history, and screen for contraindications—pregnancy, severe gastroparesis, or previous pancreatitis—before issuing a prescription. Always use our free weight loss calculator to understand projected outcomes; individual results vary significantly based on dose, diet adherence, and lifestyle factors.
- 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.
Can I get Mounjaro through a standard GP prescription in the UK?
Not typically. Mounjaro (tirzepatide) is primarily prescribed through NHS tier 3 specialist weight management services following referral from your GP. Standard GP practices do not usually prescribe it. Private online prescribing via GPhC-registered pharmacies is the main alternative to NHS specialist referral.
What eligibility criteria must I meet for Mounjaro in the UK?
You need a BMI of 30 or above, or BMI 27–29.9 with at least one weight-related health condition (type 2 diabetes, hypertension, sleep apnoea, or cardiovascular disease). South Asian, Chinese, Black African, or Black Caribbean adults may be eligible from BMI 27.5. Use our free BMI calculator above to check your current BMI.
How long are NHS waiting lists for Mounjaro through specialist services?
Waiting times vary significantly by region and local integrated care board (ICB) availability. Some areas have waiting lists of several months to over a year. Availability and prioritisation criteria differ across the UK, so contact your local weight management service for specific timescales.
Is Mounjaro more effective than Wegovy for weight loss?
Clinical trials show Mounjaro (dual GIP/GLP-1 agonist) may produce slightly greater average weight loss than Wegovy (GLP-1 agonist alone)—approximately 20.9% vs 14.9% body weight. However, individual results vary considerably. Your prescriber will advise which option suits your circumstances best.
What happens if I'm assessed for Mounjaro and deemed ineligible?
If you don't meet clinical criteria, your prescriber should discuss alternative options: NHS tier 2 services (behaviour change programmes), lifestyle interventions, or assessment for other weight management approaches. Your GP can also refer you back to specialist services if circumstances change.
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.