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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What Are the Pancreatitis Symptoms with Mounjaro?
Pancreatitis is a serious but rare side effect that can occur with Mounjaro (tirzepatide). Knowing the warning signs is essential for your safety. This guide explains the symptoms of pancreatitis to watch for, when to seek medical help, and how the NHS monitors GLP-1 and dual GIP/GLP-1 medications like Mounjaro in the UK. If you're considering Mounjaro or currently taking it, understanding this risk is an important part of informed consent and safe use.
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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.
Symptoms of Pancreatitis to Watch For
Pancreatitis is inflammation of the pancreas and requires urgent medical attention. Seek immediate help if you experience any of these warning signs while taking Mounjaro:
- Severe, sudden stomach pain in the upper left or central abdomen, often radiating to the back
- Persistent nausea or vomiting
- Abdominal tenderness or swelling
- Loss of appetite
- Yellowing of skin or eyes (jaundice)
- Increased heart rate
- Fever
The most distinctive symptom is severe upper abdominal pain spreading to the back. This is not the typical nausea or stomach discomfort commonly reported with Mounjaro — pancreatitis pain is acute and severe. Clinical data shows pancreatitis is rare but serious. Contact your GP or call NHS 111 immediately if you develop these symptoms.
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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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NHS Safety Monitoring and Mounjaro Eligibility
In the UK, Mounjaro is prescribed through NHS tier 3 specialist weight management services or via private online prescribing following clinical assessment. The MHRA (Medicines and Healthcare products Regulatory Agency) monitors all adverse effects through its Yellow Card system. Before starting Mounjaro, your prescriber should assess your risk factors for pancreatitis, including personal or family history of pancreatic disease, gallstones, or high triglycerides.
The NHS recommends that anyone prescribed GLP-1 or dual GIP/GLP-1 medications like tirzepatide should be counselled about pancreatitis symptoms and given clear instructions to seek emergency care if symptoms develop. Your GP should provide ongoing monitoring during treatment.
Mounjaro is not suitable for people with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia syndrome type 2 (MEN2). Pancreatitis risk must be balanced against the proven benefits of tirzepatide in weight management trials like SURMOUNT-1. The dual GIP/GLP-1 mechanism of Mounjaro differs from Wegovy (semaglutide), which uses a single GLP-1 pathway. Both medications carry similar risks of pancreatitis, though it remains uncommon.
- 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 should I do if I develop severe stomach pain while taking Mounjaro?
Severe upper abdominal pain spreading to the back may indicate pancreatitis and is a medical emergency. Stop taking Mounjaro and contact NHS 111 or go to A&E immediately. Do not wait for your next GP appointment. Pancreatitis requires urgent investigation and treatment to prevent serious complications.
How common is pancreatitis with Mounjaro in the UK?
Pancreatitis is a rare side effect of Mounjaro. Clinical trials did not report pancreatitis as a common adverse effect, but it is recognised as a potential serious risk. The MHRA monitors all reports through its Yellow Card system. Your prescriber will assess your individual risk factors before starting treatment.
Can I take Mounjaro if I have a history of gallstones?
People with a history of gallstones or bile duct disease may have increased pancreatitis risk. Inform your prescriber before starting Mounjaro. You may still be eligible depending on other factors, but your prescriber will weigh the benefits and risks. Regular monitoring and clear symptom awareness are essential.
Is pancreatitis risk higher with Mounjaro than Wegovy?
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) carry a similar risk of pancreatitis, though it remains rare in clinical practice. Mounjaro is a dual GIP/GLP-1 agonist whilst Wegovy is a GLP-1 agonist alone, but pancreatitis risk is not significantly different between them. Your prescriber can discuss relative risks based on your health profile.
Will my GP monitor me for pancreatitis symptoms if I'm prescribed Mounjaro through the NHS?
Yes, NHS specialist tier 3 services should provide baseline counselling on pancreatitis symptoms and risk factors. Your GP should then monitor you during treatment. If prescribed privately, ensure your prescriber provides clear safety guidance and you understand when to seek emergency care. Always report any concerning symptoms to your healthcare team immediately.
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