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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Mounjaro vs Wegovy in the UK: Cost and Access Guide
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only weight loss injections available in the UK, but accessing them works differently depending on whether you use the NHS or private prescribing. Understanding the cost, eligibility, and access routes for each medication will help you make an informed decision. This guide explains how to get both medications in the UK and what you can expect to pay.
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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.
Private Prescription Costs and NHS Access Routes
Private prescription costs: Mounjaro and Wegovy are available through UK-licensed online pharmacies following an online clinical assessment with a prescriber. Private costs typically range from £129 to £320 per month depending on the dose you're prescribed. Mounjaro KwikPen devices (four weeks' supply) cost broadly in line with Wegovy pens at equivalent doses.
- Mounjaro 5 mg weekly: approximately £150–£180/month
- Mounjaro 10 mg weekly: approximately £180–£220/month
- Mounjaro 15 mg weekly: approximately £220–£280/month
- Wegovy 0.5–1 mg weekly: approximately £130–£160/month
- Wegovy 1.7–2.4 mg weekly: approximately £180–£240/month
NHS access: Both medications are available through NHS specialist tier 3 weight management services, but access requires referral from your GP and assessment by a specialist team. NICE (National Institute for Health and Care Excellence) has approved both tirzepatide and semaglutide for NHS use, though regional availability varies significantly. Waiting lists for NHS specialist services can be several months to over a year depending on your area.
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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.
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How to Access Each Route and What to Expect
Private route: You complete an online health questionnaire and consultation with a UK-licensed prescriber (usually within 24–48 hours). If approved, a prescription is issued to a GPhC-registered pharmacy, which dispenses and ships your medication directly. This route is faster—typically accessing medication within 1–2 weeks—and doesn't require NHS referral. However, you pay the full cost privately.
NHS route: Ask your GP for referral to your local integrated care board's (ICB) specialist weight management service. You'll be assessed for eligibility based on BMI and health factors, then placed on a waiting list. Once seen by the specialist team, they'll decide which medication (if any) is appropriate and manage your treatment free of charge through the NHS. Use our free GLP-1 weight loss calculator to understand potential outcomes before your 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.
Is Mounjaro or Wegovy cheaper on the NHS?
Both are available free through the NHS if approved by a specialist weight management service. However, NHS access involves waiting lists and may not be available in all areas. Private costs are similar for both medications at equivalent doses, typically £130–£280/month depending on strength.
Can I switch between Mounjaro and Wegovy on the NHS?
Any switch between medications must be managed by your prescriber. Tirzepatide (Mounjaro) is a dual GIP/GLP-1 agonist, while semaglutide (Wegovy) is GLP-1 only—they work differently. Your specialist will advise which is most appropriate based on your individual health profile and how you've responded to treatment.
How long does private prescription for Wegovy or Mounjaro take in the UK?
Private online consultations typically take 24–48 hours for assessment and prescription. Once issued, GPhC-registered pharmacies usually dispatch within 1–2 working days. Total time from consultation to receiving your medication is usually 3–7 days. NHS routes take considerably longer due to waiting lists.
What is the difference between Mounjaro and Ozempic in the UK?
Both contain semaglutide but are different medications: Ozempic (up to 2 mg) is licensed for type 2 diabetes, whilst Wegovy (up to 2.4 mg) is licensed specifically for weight management. Ozempic is not approved for weight loss in the UK—using it off-label is not recommended. Mounjaro contains tirzepatide, a different active ingredient offering a dual mechanism.
Do I need a GP referral to access Mounjaro or Wegovy privately?
No. Private prescribing is independent of NHS services—you don't need a GP referral. You complete an online health assessment with a UK-licensed prescriber, and if approved, receive a prescription directly. However, informing your GP of any private weight loss medication you're taking is recommended for your safety.
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