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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Semaglutide vs Mounjaro: UK Cost, Access & How to Get Prescribed
Both semaglutide (Wegovy) and Mounjaro (tirzepatide) are prescription-only weight loss injections available in the UK, but they differ significantly in cost, availability, and how you access them. Understanding your options—whether through NHS specialist services or private prescription routes—is essential before deciding which might suit your situation. This guide breaks down the real costs, access pathways, and practical steps for getting either medication prescribed.
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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.
UK Private Prescription Costs: Semaglutide vs Mounjaro
Private prescription costs vary widely depending on dose and provider, but expect to pay between £129 and £320 per month for either medication through UK-registered online pharmacies.
For semaglutide (Wegovy), starting doses (0.25–0.5 mg) typically cost £129–£180/month, while maintenance doses (1.7–2.4 mg) range from £220–£280/month. For Mounjaro (tirzepatide), costs are broadly similar: starting doses (2.5–5 mg) around £150–£200/month, with higher doses (10–15 mg) reaching £280–£320/month.
Costs depend on the specific provider, your dose level, and whether you're using a standard or premium consultation service. Most private providers charge separately for the clinical consultation (typically £20–£50) and the medication itself. Always compare providers before committing, as prices and service quality vary. Some providers offer subscription discounts if you commit to longer-term treatment, though these are not assured.
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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 Access vs Private Route: What's Actually Available?
NHS access to weight loss injections is extremely limited. NICE approved tirzepatide (Mounjaro) for use within NHS specialist weight management services, but tier 3/4 services exist in only some areas, and waiting lists can stretch to 12+ months in many regions. Your GP can refer you, but availability depends entirely on your local Integrated Care Board (ICB) and waiting list capacity.
Private prescription is faster and more accessible. You complete an online clinical assessment with a UK-licensed prescriber, receive a prescription if approved, and have medication dispensed by a GPhC-registered pharmacy—often within days. You don't need an NHS referral. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses, and our BMI calculator to confirm your eligibility (BMI 30+, or 27+ with weight-related health conditions) before starting your private consultation.
- 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, semaglutide or Mounjaro, in the UK?
Costs are broadly comparable through private prescription: both typically range from £129–£320/month depending on dose. Semaglutide starts at lower doses (0.25 mg) which may cost slightly less initially, while Mounjaro's maximum dose (15 mg) can be pricier. NHS access is free but extremely limited and involves long waits.
Can I get Mounjaro or semaglutide through the NHS in the UK?
NICE approved Mounjaro for NHS specialist weight management services, but availability varies dramatically by region. Your GP can refer you to tier 3 services, though waiting lists are often 12+ months. Semaglutide (Wegovy) is less commonly available on NHS prescription. Private prescription is faster and more accessible.
What's the difference between Wegovy and semaglutide?
Wegovy is the brand name for semaglutide approved specifically for weight management in the UK (doses up to 2.4 mg). Ozempic is also semaglutide but at a lower dose (up to 2 mg) and approved for type 2 diabetes. Wegovy is the licensed weight loss version, not off-label use of diabetes medication.
How long does a private consultation take, and what happens next?
Online consultations typically take 10–15 minutes and involve questions about your medical history, current medications, and weight loss goals. If approved, you'll receive a prescription and your medication will be dispensed within a few days to a week. You'll be advised to start at the lowest dose and titrate weekly under guidance.
Is a private weight loss injection prescription safe, or should I wait for NHS?
Reputable private prescribers are UK-licensed and conduct proper clinical assessments before issuing prescriptions. However, both medications are prescription-only for good reason—they require medical suitability assessment and ongoing monitoring. Whether private or NHS, both pathways require a real clinical assessment, not just instant prescription.
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.