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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Sickness on Mounjaro: Cost and Access Options in the UK
Nausea and sickness are among the most common side effects of Mounjaro (tirzepatide), affecting many people starting this prescription weight management injection. Understanding how to access Mounjaro in the UK—whether through the NHS or privately—plus what it actually costs, can help you make an informed decision about whether this medication is right for you. This guide covers NHS eligibility, private prescription costs, and what to expect from the access process.
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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 and Mounjaro Access
Private access to Mounjaro in the UK typically costs between £129 and £320 per month, depending on your dose and the prescribing service you choose. Each KwikPen contains four weekly injections, so costs vary significantly as you titrate through doses—starting at 2.5 mg (lowest cost) and potentially reaching 15 mg (maximum dose). Private prescriptions require an online clinical assessment with a UK-licensed prescriber, after which a GPhC-registered pharmacy dispenses the medication. This route does not require an NHS referral and offers faster access than specialist services, typically within days rather than months.
- Mounjaro UK prescription costs vary by dose level and provider
- Private access is available without NHS referral within days
- Online clinical assessment determines eligibility and dose
- NHS specialist services offer free treatment but face long waiting lists in many regions
If you experience sickness on Mounjaro, your prescriber can adjust your dose, advise on symptom management, or explore whether this medication remains suitable for you.
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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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NHS vs Private: Which Route is Right for You?
NHS access to Mounjaro is available through tier 3 specialist weight management services following a GP referral, but availability and waiting times vary dramatically by region. Some ICBs (Integrated Care Boards) offer tirzepatide, whilst others do not yet commission it. NICE has approved tirzepatide for use within the NHS, but access is restricted to specialist weight management services—not routine GP prescription. The private route offers faster access and no referral requirement, whilst the NHS route is free at point of use if your local service commissions the medication. Both routes involve clinical assessment; the difference is speed and cost.
- Online consultation with a UK prescriber takes 1–2 days
- Prescription issued if clinically suitable; dispensed within 2–3 days
- NHS waiting lists can extend from weeks to years depending on your region
- 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 available on the NHS in the UK?
Yes, Mounjaro (tirzepatide) is approved by NICE for NHS use within specialist tier 3 weight management services. However, availability varies by region. You'll need a GP referral to access it. Waiting lists are often long, and not all ICBs currently commission the medication. Private prescription offers faster access without referral.
What does Mounjaro cost privately in the UK?
Private Mounjaro costs typically range from £129 to £320 per month depending on dose. Each KwikPen (four weeks of injections) is priced separately. Starting doses (2.5 mg) cost less than maintenance doses (15 mg). Costs vary between different private prescribing services, so comparing options is worthwhile.
How long does it take to get Mounjaro privately?
Private access is usually very fast. An online clinical assessment typically takes 1–2 days. If approved, a prescription is issued and dispensed by a GPhC-registered pharmacy within 2–3 days. This is significantly faster than NHS specialist services in most regions.
Is the sickness on Mounjaro the same cost as managing it on Wegovy?
Mounjaro and Wegovy are both prescription-only injections with different costs. Mounjaro starts at around £129–£200 for lower doses; Wegovy typically costs £129–£180. Both can cause nausea. Costs depend on dose and provider. Ask your prescriber which option suits your budget and health needs.
Can I use my BMI to check if I'm eligible for Mounjaro?
Eligibility for Mounjaro requires a BMI of 30 or above (or 27+ with weight-related conditions), but a clinical assessment determines final suitability. Use our free BMI calculator to check your current BMI, then discuss results with your GP or a private prescriber to confirm eligibility and whether sickness management is feasible for you.
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.