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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Wegovy vs Mounjaro in the UK — Cost and Access
Both Wegovy (semaglutide) and Mounjaro (tirzepatide) are prescription-only weight management injections licensed in the UK, but they differ significantly in cost and how you access them. If you're trying to decide between these two GLP-1 medications, understanding the price differences, prescription routes, and what each costs privately can help you make an informed choice. This guide covers current UK pricing, NHS availability, and how to get each medication.
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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 Private Cost and Access Routes
Wegovy (semaglutide) is available privately through online consultations with UK-licensed prescribers. Typical private costs range from £129–£200 per month at lower doses, rising to £180–£250 per month at the maximum 2.4 mg dose. Each dose is a once-weekly injection, so one pen contains four weeks of treatment.
Mounjaro (tirzepatide) typically costs £140–£320 per month privately, depending on dose. The wider price range reflects that tirzepatide has dual GIP and GLP-1 mechanisms, and as a newer medication, some providers price it differently. A Mounjaro KwikPen also contains four weeks of doses at a given strength.
- Both are available through GPhC-registered online pharmacies without NHS referral
- Prices vary between providers — shopping around is worthwhile
- Prescription required from a UK-licensed prescriber following an online clinical assessment
- Ongoing prescriptions may be available monthly or quarterly, depending on the provider
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 — Eligibility and Waiting Times
Through the NHS, both Wegovy and Mounjaro may be available free, but access is limited. You must be referred by your GP to a specialist tier 3 weight management service, which provides comprehensive dietary, physical activity, and behavioural support alongside medication. NICE has approved tirzepatide (Mounjaro) for NHS use, and semaglutide (Wegovy) is also available through some services.
NHS waiting lists for specialist weight management services are typically 6–18 months in many regions, though this varies by area. If you want to start treatment more quickly, private prescription is often faster — you can have a consultation within days and begin treatment within a week. Many people choose private access because NHS services cannot meet demand, making the private cost a worthwhile investment for quicker access.
An online consultation typically involves completing a health questionnaire, weight and height measurements, and sometimes a video call with a prescriber. The prescriber assesses your eligibility based on your BMI, health conditions, and medication history. Use our free BMI calculator above to check your personal BMI before your consultation — this helps both you and the prescriber understand your baseline. If approved, a prescription is issued and your medication is posted by a GPhC-regulated pharmacy. You'll also track your progress using our GLP-1 weight loss calculator to monitor projected results at your chosen dose.
- 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.
Which is cheaper — Wegovy or Mounjaro in the UK?
Privately, Wegovy typically costs £129–£250 per month, while Mounjaro usually costs £140–£320 per month depending on dose. Prices vary between providers, so it's worth comparing. Both are free through the NHS if prescribed via specialist weight management services, but NHS access involves waiting lists and GP referral.
Can I get Mounjaro on the NHS in the UK?
Yes — Mounjaro (tirzepatide) is approved by NICE for NHS use within specialist tier 3 weight management services. You need GP referral to access it. NHS waiting times vary by region, typically 6–18 months. Private prescription offers faster access but involves monthly costs.
What's the difference between a KwikPen and a standard syringe?
Mounjaro comes as a pre-filled KwikPen with four doses at a set strength. Wegovy comes as a pre-filled auto-injection pen, also with four doses. Both are once-weekly injections — you cannot adjust the dose mid-week. The KwikPen design is slightly different but both are straightforward to use at home.
Do I need a GP referral to get Wegovy or Mounjaro privately?
No — for private prescription, you contact a GPhC-registered online pharmacy or prescriber directly. You complete an online health questionnaire and consultation (sometimes a video call) with a UK-licensed prescriber. If approved, a prescription is issued without NHS involvement. Private access bypasses the GP referral route entirely.
How long does a private prescription take to start?
Online consultations are typically available within 24–72 hours. If approved, your prescription is sent to the pharmacy, and medication is usually posted within 2–5 working days. You can begin treatment within a week of starting the process, which is much faster than NHS specialist 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.