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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Does Mounjaro Cause Pancreatitis?
Pancreatitis is a rare but serious side effect that has been reported with Mounjaro (tirzepatide) and other GLP-1 medications. It is not common, but you should know the warning signs and when to seek urgent medical attention. This guide explains pancreatitis risk with Mounjaro in the UK context, who is at higher risk, what symptoms to watch for, and how to use Mounjaro safely. Always consult your GP or prescriber if you have concerns about your individual risk.
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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.
Pancreatitis and Mounjaro — What the Evidence Shows
Pancreatitis (inflammation of the pancreas) was reported in clinical trials and post-market monitoring of Mounjaro, though cases were rare. Mounjaro's product information lists pancreatitis as a potential side effect. The exact mechanism is not fully understood, but GLP-1 and dual GIP/GLP-1 agonists like tirzepatide may affect pancreatic function. Post-market data suggests pancreatitis risk is very low, but it remains a serious concern that requires awareness.
- Cases of acute pancreatitis have been reported with GLP-1 medications globally
- Risk appears low compared to the overall population taking Mounjaro
- Severe gastric symptoms (nausea, vomiting) may increase risk slightly
- Pre-existing pancreatic conditions increase monitoring importance
- Always report persistent stomach pain to your GP immediately
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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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Warning Signs and When to Seek Help
Seek urgent medical attention if you experience sudden, severe upper abdominal pain that radiates to your back — this is a hallmark sign of acute pancreatitis and requires emergency care. Other warning signs include persistent vomiting, inability to keep food down, rapid heartbeat, or fever. If you have a history of pancreatitis, gallbladder problems, or very high triglycerides, inform your prescriber before starting Mounjaro. Your GP or A&E department can assess whether symptoms are pancreatitis-related through blood tests. Do not delay seeking help if you have severe stomach pain.
- 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.
What are the first signs of pancreatitis with Mounjaro?
Sudden severe upper abdominal pain, often radiating to the back, is the primary sign. Other symptoms include persistent vomiting, inability to keep food down, and fever. Report any severe stomach pain to your GP or A&E immediately — do not wait to see if it improves on its own.
How common is pancreatitis with Mounjaro?
Pancreatitis is rare with Mounjaro. Clinical trials and post-market monitoring have recorded cases, but they remain uncommon. Most people taking Mounjaro do not develop pancreatitis. However, any risk of a serious condition requires awareness and prompt reporting of symptoms.
Am I at higher risk of pancreatitis with Mounjaro?
Risk may be slightly higher if you have a history of pancreatitis, gallbladder disease, or very high triglycerides. Severe nausea and vomiting may also increase risk. Discuss your individual risk with your prescriber before starting — they can assess whether Mounjaro is appropriate for you.
Can I continue Mounjaro if I have mild stomach pain?
Mild nausea or stomach discomfort is common with Mounjaro, especially when starting or increasing doses. However, sudden severe pain, particularly in the upper abdomen radiating to the back, is different and requires urgent evaluation. Contact your GP or prescriber to distinguish between normal side effects and potential pancreatitis.
What should I do if I suspect pancreatitis while taking Mounjaro?
Stop taking Mounjaro and seek immediate medical attention at your GP surgery or A&E. Describe your symptoms clearly — especially the location and severity of pain. Blood tests (amylase and lipase levels) can confirm pancreatitis. Your medical team will advise whether you can safely restart Mounjaro after assessment.
Ready to take control of your weight loss journey?
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