Pancreatitis — inflammation of the pancreas — is listed as an uncommon but potentially serious side effect of all GLP-1 medications. It's one of the risks that gets the most attention, so let's look at what the data actually shows.
How common is it?
According to the patient information leaflets for both Mounjaro and Wegovy, acute pancreatitis affects approximately 1 in 100 people (classified as "uncommon" in medical terms). This means that for every 100 people taking the medication, roughly 1 may develop pancreatitis during treatment.12
It's worth putting this in context: pancreatitis also occurs in the general population, and people with obesity are already at higher risk due to factors like gallstones and high triglycerides. The question of how much GLP-1 medications increase the baseline risk, versus how much they're associated with pancreatitis in a population already predisposed to it, is still being studied.
Symptoms to know
Acute pancreatitis typically presents with:
- Severe, persistent pain in the upper abdomen — often described as boring or radiating through to the back
- Nausea and vomiting — more severe than the normal GLP-1 nausea
- Tenderness when touching the abdomen
- Fever in some cases
The key distinction from normal GLP-1 side effects is the severity and persistence of the pain. Normal nausea from GLP-1 medications is uncomfortable but manageable. Pancreatitis pain is severe and doesn't go away with simple measures.
What to do if you suspect pancreatitis
Stop taking the medication immediately and seek medical help. Call NHS 111 or go to A&E if the pain is severe. Your doctor will typically check blood lipase or amylase levels and may arrange imaging to confirm the diagnosis.1
If pancreatitis is confirmed, you should not restart the GLP-1 medication. A history of pancreatitis is a contraindication for future use of GLP-1 medications.
Who is at higher risk?
Certain factors increase pancreatitis risk regardless of medication use. These include a history of gallstones, high triglyceride levels, heavy alcohol consumption, and a previous episode of pancreatitis. If you have any of these risk factors, discuss them with your prescriber before starting a GLP-1 medication.1
Should this stop you from using GLP-1 medications?
For most people, no. A 1 in 100 risk means that 99 out of 100 people will not experience pancreatitis. The benefits of significant weight loss (reduced risk of Type 2 diabetes, heart disease, joint problems, and many other conditions) typically outweigh this relatively small risk for people who meet the prescribing criteria. But awareness of the symptoms is important so you can act quickly if needed.