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
Free tracker included with every download this week
Switching from Mounjaro to Wegovy in the UK
If you're currently taking Mounjaro (tirzepatide) and considering switching to Wegovy (semaglutide), you'll want to understand the cost, access options, and practical steps involved in the UK. Both are prescription-only GLP-1-based weight loss injections, but they differ in price, availability, and how you access them. This guide covers NHS routes, private prescription costs, and what the switching process looks like so you can make an informed decision with your healthcare provider.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Wegovy Costs in the UK and Access Routes
Private prescription costs for Wegovy in the UK typically range from £129 to £320 per month depending on the dose and provider, with costs generally higher at maximum dose (2.4 mg). This is broadly similar to Mounjaro pricing in the private market, though individual provider costs vary significantly.
NHS access to Wegovy is available through specialist tier 3 weight management services, though availability varies considerably by region and integrated care board (ICB). Most GPs can refer you to these services, but waiting lists can be lengthy — often months to over a year in many areas. Once prescribed through the NHS, Wegovy is dispensed free on prescription.
Private access is typically faster: you complete an online clinical assessment with a UK-licensed prescriber, receive a prescription if appropriate, and have Wegovy dispensed by a GPhC-registered pharmacy. The entire process often takes 48 hours to a week. Your GLP-1 weight loss calculator can help you understand dose projections before discussing costs with a prescriber.
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.
Switching from Mounjaro to Wegovy — What to Expect
Before switching, discuss with your prescriber whether a direct transition is appropriate. Mounjaro and Wegovy use different mechanisms — Mounjaro is a dual GIP/GLP-1 agonist whilst Wegovy is GLP-1 only, so your body may respond differently. Your prescriber may recommend stopping Mounjaro for a short period, or transitioning directly depending on your situation.
There's no official conversion chart, but approximate dose equivalence is: Mounjaro 5 mg ≈ Wegovy 0.5 mg; Mounjaro 10 mg ≈ Wegovy 1.7 mg; Mounjaro 15 mg ≈ Wegovy 2.4 mg. Your prescriber will advise the appropriate starting dose for Wegovy based on your medical history and mounjaro dose titration experience. Storage and injection technique are similar between both medications, making the practical transition straightforward.
- 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.
Can I switch directly from Mounjaro to Wegovy without a break?
In many cases yes, but it depends on your individual circumstances. Some prescribers recommend a direct transition, whilst others prefer a short break between medications. Always discuss with your GP or prescriber before switching — they'll assess whether continuous treatment or a gap is appropriate for your health.
Will Wegovy cost less than Mounjaro on private prescription in the UK?
Pricing is generally similar, though both vary by provider and dose. Wegovy at maximum dose (2.4 mg) often costs £200–£320/month privately, comparable to Mounjaro 15 mg. NHS prescription costs nothing if you access through specialist services, but waiting times can be significant.
How long does it take to get Wegovy through the NHS versus private prescription?
NHS route typically involves GP referral to tier 3 services, with waiting lists of weeks to over a year depending on your region. Private online prescription routes are usually faster — often 48 hours to a week from consultation to first dose.
What if Wegovy doesn't work as well as Mounjaro for me?
Individual responses vary significantly between the two medications. If Wegovy isn't as effective, you can discuss switching back to Mounjaro or trying other options with your prescriber. Many people respond differently to GLP-1-only versus dual GIP/GLP-1 mechanisms.
Do I need to restart dose titration when switching to Wegovy?
Typically yes. Wegovy has its own dose titration schedule starting at 0.25 mg, even if you were at a higher Mounjaro dose. Your prescriber may use clinical judgement to progress doses more quickly if appropriate, but you won't start at 2.4 mg directly.
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.