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 Injections in the UK
Weight loss injections like Mounjaro and Wegovy can be expensive, but there are ways to find more affordable options in the UK. Prices vary significantly depending on whether you access treatment through the NHS or privately, and the specific medication and dose you need. This guide explains the costs of each prescription weight loss injection available in the UK and how to find the most affordable option for your situation.
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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.
Weight Loss Injection Costs in the UK
Three prescription weight loss injections are currently licensed in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Costs vary significantly:
- Wegovy: typically £129–£200 per month privately, depending on dose (0.5 mg to 2.4 mg). Starting doses cost less than maintenance doses.
- Mounjaro: usually £150–£250 per month privately, with costs varying by dose (2.5 mg to 15 mg).
- Saxenda: generally £120–£150 per month privately. It's the oldest GLP-1 injection and may be cheaper than newer options at some providers.
Prices shown are approximate and vary between private prescribing services. Shopping around between GPhC-registered online pharmacies can help you find the cheapest weight loss injections available.
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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: Which Option Is Cheaper?
NHS access is free but slow: If you qualify for NHS weight management treatment, the cost is £0 — medications are provided by the NHS. However, access is through specialist tier 3 weight management services and requires a GP referral. Waiting times can be months or even years in many areas.
Private access is immediate but costs money: Private prescribing through GPhC-registered online pharmacies costs between £129–£250 per month depending on medication and dose, but you can start within days of a clinical assessment. For lose weight UK patients prioritising speed, private may be better value despite higher cost.
Use our free GLP-1 weight loss calculator to estimate which dose might be appropriate for you, and our BMI calculator to check your starting point — this information helps you compare costs more accurately across providers.
How to Find the Cheapest Weight Loss InjectionsTo access the cheapest weight loss medication UK options:
- Compare private providers: Get quotes from multiple GPhC-registered online pharmacies. Prices vary by 20–30% between providers for the same dose.
- Start with lower doses: Starting doses (0.25 mg Wegovy, 2.5 mg Mounjaro) cost less. You'll escalate over weeks, so early months are cheaper.
- Consider Saxenda: As a daily injection, Saxenda is often cheaper per month than once-weekly options, though it requires daily administration.
- Check NHS eligibility: Ask your GP about referral to specialist weight management UK services. If you qualify and waiting times are acceptable, NHS is free.
- Use our progress tracker to monitor results — avoid wasting money on injections that aren't working for you personally.
- 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?
Saxenda (liraglutide) is often the cheapest at approximately £120–£150 per month privately. However, it's a daily injection rather than once-weekly. Wegovy starts around £129 per month for lower doses. Compare multiple GPhC-registered providers as costs vary significantly.
Can I get weight loss injections free on the NHS?
Yes, but only through specialist tier 3 weight management services following GP referral. You must meet eligibility criteria (BMI ≥30 or ≥27 with weight-related conditions). NHS availability and waiting times vary significantly by region. Ask your GP about local services.
How much does Mounjaro cost compared to Wegovy?
Mounjaro typically costs £150–£250 per month privately, slightly more than Wegovy (£129–£200). Costs depend on dose — starting doses are cheaper than maintenance doses. In clinical trials, Mounjaro showed slightly higher average weight loss than Wegovy, though individual results vary.
Is it cheaper to buy weight loss injections abroad?
Importing prescription medications into the UK is illegal without a valid UK prescription for personal use. Always use GPhC-registered UK pharmacies. Counterfeit or unregulated medications carry serious health risks. Stick to legitimate UK providers.
Do cheaper weight loss injections work as well as expensive ones?
The same medication at the same dose works the same way regardless of price. Price differences reflect provider overheads and business models, not medication quality. All NHS and GPhC-registered private pharmacies supply genuine, regulated medications. Individual results depend on dose, adherence, and lifestyle changes, not cost.
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.