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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Pancreatitis On Mounjaro — What UK Adults Need to Know
Pancreatitis is a rare but serious side effect that can occur with Mounjaro (tirzepatide). This guide explains what pancreatitis is, how to recognise warning signs, and when to seek immediate medical attention. If you're considering Mounjaro or currently taking it via NHS specialist services or private prescription, understanding this risk is essential. This information is for general educational purposes and does not replace advice from your GP or healthcare professional.
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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.
Understanding Pancreatitis Risk With Mounjaro
Pancreatitis is inflammation of the pancreas, a gland that produces digestive enzymes and insulin. While serious, it is a rare side effect of Mounjaro — clinical trials did not report pancreatitis as a common occurrence. However, GLP-1 and GIP/GLP-1 receptor agonists like Mounjaro (tirzepatide) can theoretically trigger pancreatitis, particularly in people with a personal or family history of gallbladder disease or pancreatic conditions.
Key risk factors for pancreatitis on Mounjaro include:
- gradual weight management causing gallstones (gallstone pancreatitis)
- History of pancreatitis or pancreatic disease
- Family history of pancreatitis
- Severe hypertriglyceridaemia (very high triglycerides)
- Certain medications that increase pancreatitis risk
Your prescriber will assess your individual risk when considering whether Mounjaro is suitable for you. If you have any of these risk factors, inform your healthcare team before starting treatment.
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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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Recognising Pancreatitis Symptoms — When to Seek Help
Seek urgent medical attention immediately if you experience:
- Severe, persistent upper abdominal pain (often spreading to the back)
- Abdominal pain accompanied by vomiting
- Severe nausea or inability to keep food or liquid down
- Pain that worsens when lying flat or after eating fatty foods
- Yellowing of skin or eyes (jaundice)
- Fever with abdominal pain
Do not wait to see your GP — go to A&E or call 999 if you suspect pancreatitis. Early diagnosis and treatment are critical. Pancreatitis requires urgent hospital assessment, blood tests (amylase and lipase levels), and imaging. If pancreatitis is confirmed, you will likely need to stop Mounjaro immediately and may require hospital admission.
- 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 get pancreatitis from Mounjaro even if I have no risk factors?
Pancreatitis is rare with Mounjaro, and most people taking it do not develop it. However, any medication carries potential risks. Your prescriber will assess your individual risk profile during clinical assessment. If you have concerns, discuss them with your GP or the prescriber conducting your online consultation.
Is pancreatitis more common with Mounjaro than with Wegovy?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) carry a theoretical pancreatitis risk as GLP-1-based medications. Clinical trial data show pancreatitis is rare with both. Your NHS specialist service or private prescriber will discuss which medication is most appropriate based on your health profile.
What should I do if I've had gallstones before and want to try Mounjaro?
Tell your prescriber or GP about your gallstone history before starting. gradual weight management can trigger gallstone-related pancreatitis. Your healthcare team may recommend closer monitoring, slower weight loss goals, or an alternative medication. Never start Mounjaro without disclosing previous gallbladder issues.
If I stop Mounjaro due to pancreatitis symptoms, can I restart it later?
If pancreatitis is confirmed, Mounjaro must be stopped and should not be restarted. Your GP or specialist will discuss alternative weight management approaches. Do not attempt to restart without explicit medical guidance — pancreatitis recurrence is a serious risk.
How can I monitor myself safely while taking Mounjaro through NHS or private prescription?
Keep a symptom diary, know the warning signs of pancreatitis, and seek immediate help if you experience severe abdominal pain. Attend all follow-up appointments with your prescriber. Use our free BMI calculator and progress tracker to monitor weight loss pace — very gradual weight management may increase gallstone risk.
Ready to take control of your weight loss journey?
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