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 Tirzepatide Online in the UK
Tirzepatide is a GLP-1 and GIP receptor agonist injectable medication licensed in the UK for weight management in adults. If you're searching for tirzepatide online, you have two main routes: NHS specialist services or private prescribing. This guide explains UK eligibility, how the NHS tier system works, and what to expect from private online access. Both pathways require a clinical assessment before tirzepatide is prescribed — there is no completely unregulated route in the UK.
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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 to Tirzepatide: Eligibility & NICE Guidance
NICE approved tirzepatide (Mounjaro) for use within NHS specialist weight management services in 2024. However, access is not through your GP directly — it requires referral to a tier 3 or tier 4 specialist weight management service in your local Integrated Care Board (ICB). Eligibility criteria include:
- BMI of 30 kg/m² or above, OR
- BMI of 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease)
- For South Asian, Black African, or Black Caribbean adults, lower BMI thresholds may apply (from 27.5 kg/m²)
NHS waiting lists for specialist services are very long in many areas — months to years in some regions. If you want faster access, private online prescribing is an alternative route.
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.
Private Online Tirzepatide: Speed & Cost vs NHS
Private online prescribing allows you to access tirzepatide without waiting for NHS referral. You'll complete an online clinical assessment with a UK-licensed prescriber, and if approved, receive a prescription dispensed by a GPhC-registered pharmacy. This typically takes 3–7 days from assessment, versus NHS waiting lists of many months. Costs range from approximately £130–£320 per month depending on the dose. Private access does not replace NHS care — you can still use the NHS for monitoring and support alongside private prescriptions. Use our GLP-1 weight loss calculator to estimate potential results at different doses, and our BMI calculator to check your current BMI against NHS eligibility thresholds.
- 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 tirzepatide prescribed online in the UK without seeing my GP?
Yes. Private online prescribing allows you to have a clinical assessment with a UK-licensed prescriber without involving your GP. However, you should inform your GP you're taking tirzepatide, especially if you're on other medications. NHS access still requires GP referral to a specialist service.
What's the difference between NHS and private tirzepatide access?
NHS access is through specialist weight management services (typically free) but involves waiting lists of many months. Private online access is faster (3–7 days) and doesn't require NHS referral, but costs £130–£320 per month depending on dose. Both require clinical assessment.
Am I eligible for tirzepatide on the NHS?
NHS eligibility requires a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with a weight-related health condition. For South Asian, Black African, or Black Caribbean adults, thresholds may be lower. Your GP or a specialist can assess your eligibility.
How does tirzepatide work for weight loss?
Tirzepatide is a GIP and GLP-1 receptor agonist that reduces appetite, increases feelings of fullness, and slows gastric emptying. Clinical trials showed average weight loss of 15–21% body weight over 72 weeks, alongside diet and exercise — but individual results vary significantly.
Is tirzepatide (Mounjaro) the same as semaglutide (Wegovy)?
No. Tirzepatide uses dual GIP and GLP-1 mechanisms, while semaglutide is a GLP-1 agonist only. Both are licensed in the UK for weight management, but they're different medications with different dosing schedules. Clinical trials show slightly higher average weight loss with tirzepatide, though results vary.
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.