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 Throwing Up — Understanding Cost and Access in the UK
Nausea and vomiting are common side effects of Mounjaro (tirzepatide), particularly when starting treatment or increasing your dose. If you're experiencing throwing up, it's important to understand your treatment options and what they cost in the UK. This guide covers private prescription costs, NHS access routes, and how to manage side effects while using this GLP-1 dual agonist weight management injection. Whether you're considering Mounjaro or already taking it, knowing your cost and access options helps you make informed decisions about your weight management journey.
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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 Cost and Private Prescription Access in the UK
Private prescription costs for Mounjaro in the UK typically range from £140 to £320 per month, depending on your dose and the online prescribing service you use. Starting doses (2.5 mg) are usually at the lower end, while higher maintenance doses (15 mg) cost more. Each KwikPen contains 4 weeks of injections, so monthly costs apply per pen.
- Starter dose (2.5–5 mg): approximately £140–£180/month
- Maintenance doses (7.5–10 mg): approximately £200–£260/month
- Higher doses (12.5–15 mg): approximately £280–£320/month
Private access involves an online clinical assessment with a UK-licensed prescriber. If approved, your prescription is dispensed by a GPhC-registered pharmacy. You can use our free GLP-1 weight loss calculator to estimate potential results at different doses, helping you understand what you might expect for the cost. Storage requires a refrigerator at 2–8°C before first use, or room temperature (below 30°C) for up to 30 days after opening.
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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.
NHS vs Private Access: Routes and Timeline
NHS access to Mounjaro is through specialist tier 3 weight management services, typically after GP referral. NICE has approved tirzepatide for NHS use, but regional availability varies significantly and waiting lists can extend months or years. Private prescribing bypasses NHS waiting lists—you can start treatment within days of your online assessment if approved.
The online consultation process involves completing a health questionnaire, reviewing your medical history, and discussing your weight management goals with a prescriber. They assess your eligibility (BMI 30+ or 27+ with weight-related health conditions) and check for contraindications before issuing a prescription. Track your progress using our free progress tracker once you begin treatment, and use the BMI calculator to monitor changes in your BMI category over time.
- 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.
Why does Mounjaro cause throwing up and vomiting?
Nausea and vomiting occur because Mounjaro activates GLP-1 and GIP receptors, which slow stomach emptying and reduce appetite. These effects are usually strongest when starting treatment or increasing your dose. Symptoms typically improve over 1–2 weeks as your body adjusts, though they affect individuals differently.
How much does Mounjaro cost on the NHS in the UK?
Mounjaro is free when prescribed through NHS specialist weight management services. However, NHS access requires specialist referral and can involve long waiting lists. Costs are covered by the NHS once you're accepted into a tier 3 service, but availability varies significantly by region and integrated care board.
Can I get Mounjaro on prescription privately if I'm experiencing side effects?
Yes. If you're experiencing throwing up or other side effects, a UK-licensed prescriber can assess whether continuing Mounjaro is appropriate, adjusting your dose or discussing alternatives like Wegovy. Private prescribers can assess your individual situation and manage side effects more flexibly than some NHS pathways.
What's the difference between getting Mounjaro privately versus NHS?
NHS access is free but requires specialist referral and has variable waiting times across regions. Private costs £140–£320/month depending on dose but offers faster access (days vs months/years). Both routes require clinical assessment; private offers more flexibility in dose management and timing.
How do I know if Mounjaro's cost is worth it for my weight management?
Our free GLP-1 weight loss calculator helps you estimate potential weight loss outcomes at different doses. Clinical trials show average weight loss of 15–21% of body weight, though individual results vary. Compare this against the cost and discuss with a prescriber whether the investment aligns with your health goals.
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.