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
Mounjaro Feeling Sick — UK Access & Cost Guide
Feeling sick or nauseous is one of the most common side effects when starting Mounjaro (tirzepatide) in the UK. Nausea typically occurs during the initial weeks as your body adjusts to the medication, and it often improves over time. Understanding why this happens, how to manage it, and what Mounjaro costs through NHS or private routes can help you make an informed decision. Whether you're considering starting Mounjaro or already experiencing nausea, this guide covers the practical and financial aspects of accessing this prescription-only weight management injection in the UK.
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.
Mounjaro Nausea: Why It Happens & Managing Side Effects
Nausea is reported by more than 1 in 10 people taking Mounjaro, making it one of the most frequent side effects, particularly during the first 4 weeks on each new dose. This occurs because tirzepatide slows how quickly food leaves your stomach (gastric emptying) and also signals to your brain that you feel fuller—both of which can trigger nausea as your body adjusts.
Managing nausea while on Mounjaro includes:
- Eating smaller, more frequent meals rather than large portions
- Avoiding fatty, greasy, or heavily spiced foods
- Staying hydrated with water and electrolyte drinks
- Eating slowly and chewing food thoroughly
- Avoiding strong food smells or triggers
- Taking ginger supplements or sipping ginger tea
- Resting after meals and avoiding vigorous exercise immediately after eating
In most cases, nausea reduces significantly after 1–2 weeks on each dose. If severe nausea persists beyond this or causes vomiting, contact your GP or prescriber—they may recommend a slower dose escalation or anti-nausea medication. Never stop taking Mounjaro suddenly without medical advice.
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.
Mounjaro Cost & Access in the UK: NHS vs Private Routes
NHS access: Mounjaro is available through NHS specialist tier 3 weight management services, but availability varies by region and waiting lists can be months to years long. You'll need a GP referral and assessment by a specialist team. This route is free at the point of use.
Private prescription route: Adults can access Mounjaro privately through UK-licensed prescribers via online consultations, typically costing £129–£250+ per month depending on dose and provider. The Mounjaro KwikPen contains 4 weeks of doses. A clinical assessment is required before prescription. Use our GLP-1 weight loss calculator to explore potential outcomes and compare with other options like Wegovy before committing financially.
Private online consultations typically take 10–15 minutes and assess your BMI, medical history, current medications, and weight-related health conditions. You'll receive a prescription if clinically appropriate, which is then dispensed by a GPhC-registered pharmacy. Private treatment is not subsidised, so ongoing costs should be factored into your decision. Some people use the BMI calculator on this page to confirm their eligibility before pursuing either route.
- 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.
How long does Mounjaro nausea last?
Nausea typically peaks in the first 2–3 days after injection and gradually improves over the next 7–10 days. Most people report significant improvement by week 2–4 on each dose. If nausea persists beyond 2 weeks or worsens, contact your GP or prescriber.
Can I take anti-sickness medication with Mounjaro?
Yes, your GP or prescriber can recommend anti-nausea medications if needed. Common options include ginger supplements, acupressure bands, or prescription anti-emetics. Always inform your prescriber of all medications you're taking, as tirzepatide may affect absorption of oral medicines.
Is Mounjaro available on the NHS in my area?
Availability varies significantly by region and ICB (Integrated Care Board). Contact your GP to enquire about specialist tier 3 weight management services in your area. You may need to be referred and assessed before access is approved. Waiting times vary from months to over a year in some regions.
What's the difference between NHS and private Mounjaro costs?
NHS access is free at the point of use but requires specialist referral and may involve waiting lists. Private Mounjaro costs approximately £129–£250+ per month depending on dose. Each KwikPen contains 4 weekly doses. Private routes are faster but require payment.
Can nausea from Mounjaro mean the dose is too high?
Not necessarily. Nausea is a normal adjustment response, not a sign of overdosing. However, if you experience severe vomiting or persistent nausea beyond 2 weeks, your prescriber may recommend a slower dose escalation or temporary dose reduction to allow your body more time to adjust.
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.