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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Weight Loss Injections: UK Cost and Medication Options
Weight loss injections are prescription-only medications available in the UK for eligible adults struggling with excess weight. The cost varies significantly depending on whether you access treatment through the NHS or privately, and which medication your prescriber recommends. This guide explains the UK-licensed options, typical costs, and how to find out if you're eligible for prescription 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.
UK-Licensed Weight Loss Injections and Pricing
Three UK-licensed prescription weight loss injections are currently available for eligible adults:
- Mounjaro (tirzepatide) — once-weekly injection, typically £129–£250+ per month depending on dose. Dual GLP-1 and GIP receptor agonist. Clinical trials showed average weight loss of 15–21% body weight.
- Wegovy (semaglutide) — once-weekly injection, typically £140–£320 per month at the maximum dose. GLP-1 receptor agonist. Average weight loss around 15% body weight in clinical trials.
- Saxenda (liraglutide) — once-daily injection, typically £120–£200 per month. GLP-1 receptor agonist. Average weight loss around 5–6% body weight.
Individual results vary and depend on the dose, your starting weight, diet, and activity levels. Costs shown are approximate private prescribing rates and may vary between providers.
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.
NHS vs Private Access: Which Route Is Right for You?
NHS access is free but limited. Specialist tier 3/4 weight management services across the UK may prescribe these medications, but availability varies significantly by region and waiting lists can be months or years. You'll need a GP referral to a specialist service.
Private access is faster. GPhC-registered online pharmacies can issue prescriptions following an online clinical assessment, with no NHS referral needed. You pay the full cost of medication, but access is typically within days rather than months.
Your GP can advise which route suits your circumstances and eligibility. Try our GLP-1 weight loss calculator to estimate potential weight loss with different medications, and use our BMI calculator to check if you fall within eligible BMI ranges for prescription treatment.
- 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 much do weight loss injections cost privately in the UK?
Private costs vary by medication and dose. Mounjaro typically costs £129–£250+ per month, Wegovy £140–£320 per month (at maximum dose), and Saxenda £120–£200 per month. Prices vary between GPhC-registered pharmacy providers. Some providers offer tiered pricing for maintenance doses.
Are weight loss injections free on the NHS?
Yes, if prescribed through NHS specialist weight management services. However, access is limited and varies by region. You'll need a GP referral and may face a waiting list. Private prescribing costs are not covered by the NHS unless specifically agreed as part of a shared care arrangement.
Who is eligible for prescription weight loss injections in the UK?
Adults with a BMI of 30 or above, or BMI 27–29.9 with a weight-related health condition (type 2 diabetes, high blood pressure, high cholesterol, sleep apnoea, or cardiovascular disease) may be eligible. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds. A prescriber assesses individual eligibility.
What's the difference between Mounjaro and Wegovy in terms of effectiveness and cost?
Mounjaro showed average weight loss of 15–21% body weight in trials, while Wegovy showed around 15%. Mounjaro is a dual GIP/GLP-1 agonist (different mechanism), Wegovy is GLP-1 only. Costs overlap significantly (£129–£320/month range), so cost difference depends on your dose and provider.
How do I find out if I'm eligible for weight loss injections on the NHS?
Speak to your GP, who can assess your eligibility and refer you to your local specialist weight management service if appropriate. Eligibility depends on your BMI, health conditions, and previous weight management attempts. Private online prescribers can also assess eligibility if you're considering private treatment.
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.