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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Cheapest Weight Loss Injection in the UK
If you're looking for affordable weight loss injections in the UK, several prescription options are available at different price points. The cost of GLP-1 and dual-action weight management medications varies significantly depending on whether you access them through the NHS or private prescribing services. This guide explains the cheapest weight loss medication options available, how eligibility works, and realistic costs for prescription weight loss treatment 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.
UK-Licensed Weight Loss Injections and Their Costs
Three prescription weight loss injections are currently licensed in the UK for weight management:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, injected once weekly. Private costs typically range from £129–£320 per month depending on dose (starting at 2.5 mg, up to 15 mg maximum).
- Wegovy (semaglutide) — a GLP-1 receptor agonist, injected once weekly. Private pricing usually £150–£280 per month for doses ranging from 0.25 mg to 2.4 mg.
- Saxenda (liraglutide) — a GLP-1 receptor agonist, injected daily. Typically the most expensive option at £180–£350 per month due to daily dosing, with doses from 0.6 mg to 3 mg daily.
All three are prescription-only medicines requiring clinical assessment before supply. Mounjaro and Wegovy tend to offer the lowest cost-per-week options due to once-weekly dosing, making them generally the cheapest weight loss injection choices for most UK users.
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: How to Access Affordable Weight Loss Treatment
The cheapest option is NHS provision if you're eligible and can access your local specialist weight management service. NHS weight loss medication is free at point of use, but availability varies by region and waiting lists can extend to months or years. To access NHS treatment, ask your GP for referral to your local Integrated Care Board (ICB) tier 3 weight management service. Eligibility requires a BMI of 30 or above (or 27+ with weight-related health conditions), plus evidence of prior weight loss attempts. If NHS waiting times are too long, private online prescribing offers faster access, with costs from £129 monthly for the lowest-dose options. Use our GLP-1 weight loss calculator to estimate potential results at different doses, and our BMI calculator to confirm your eligibility threshold.
For the absolute cheapest weight loss injection in the UK, NHS provision is unbeatable, but private access provides faster pathways. Most private providers require an online consultation (typically £20–£50) and supply costs of £129–£320 monthly depending on dose. Some online services offer loyalty discounts or multi-month payment plans. When comparing weight management options, consider the dose you'll likely need — starting doses (Mounjaro 2.5 mg or Wegovy 0.25 mg) are often cheaper than maintenance doses. Track your progress with our free progress tracker to ensure your chosen treatment is delivering results.
- 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.
What's the cheapest weight loss injection available in the UK?
Mounjaro and Wegovy at their lowest doses (2.5 mg and 0.25 mg respectively) typically cost around £129–£150 monthly through private prescribing — the most affordable licensed options. NHS provision is completely free but requires GP referral to specialist services and may have waiting lists. Saxenda, being a daily injection, is generally more expensive.
Can I get weight loss injections free on the NHS?
Yes, if eligible and referred to a specialist tier 3 weight management service by your GP. However, NHS availability varies significantly by region and waiting times can be very long. Eligibility requires BMI ≥30 (or ≥27 with weight-related health conditions) and evidence of prior weight loss attempts. Ask your GP about your local ICB services.
How much does a month's supply of Mounjaro cost privately?
Mounjaro costs approximately £129–£200 monthly for doses 2.5–5 mg, and £200–£320 for higher doses (10–15 mg). Pricing varies by pharmacy and dose. Starting doses are significantly cheaper. Many providers offer payment plans or loyalty discounts for ongoing treatment.
Is there a cheaper alternative to GLP-1 weight loss injections?
If prescription injections are unaffordable, discuss alternatives with your GP: lifestyle programmes, low-calorie diet support, or NHS digital weight management tools are free. Some areas offer NHS community weight management programmes before specialist referral. Your GP can advise based on your circumstances.
How do I find the cheapest weight loss injection provider?
Compare private prescribing services online — prices vary between £129–£320 monthly for the same medication. Request quotes at your starting dose. Ask about multi-month discounts or loyalty schemes. NHS access is free if you can access specialist services — ask your GP about local tier 3 weight management services.
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.