Users of GLP-1 injections such as Ozempic, Mounjaro, and Wegovy are being urged to stay alert to a rare but potentially serious side effect. The Medicines and Healthcare products Regulatory Agency (MHRA) has stressed the importance of both patients and healthcare professionals being aware of the warning signs to look out for.
Risk of Pancreatic Inflammation
The MHRA had previously flagged the risk to those taking GLP-1 medications of developing severe pancreatic inflammation. Earlier this year, it notified doctors and patients about which symptoms to monitor, warning that anyone experiencing them should seek immediate medical attention.
The pancreas is a small organ located behind the stomach that assists with digestion. It can, however, become inflamed and swollen, causing persistent and severe abdominal and back pain. When this happens suddenly, it is known as acute pancreatitis. While most people generally begin to recover within around a week without further complications, those suffering from severe acute pancreatitis may face more serious consequences, according to the NHS.
Updated Product Information
Recently, the MHRA updated product information for both healthcare professionals and patients — including those taking the medication for weight loss — to ensure awareness of this risk. Alison Cave, the MHRA's Chief Safety Officer, said at the time: "Patient safety is the MHRA's top priority and we continually monitor the safety and efficacy of all licensed medicines."
"For the vast majority of patients who are prescribed GLP-1s, they are safe and effective medicines which deliver significant health benefits. The risk of developing these severe side effects is very small, but it is important that patients and healthcare professionals are aware and alert to the associated symptoms."
"If you, or someone you care for, is taking GLP-1s and you notice symptoms such as severe, persistent stomach pain that may radiate to the back and may be accompanied by nausea and vomiting, then we advise you speak to a healthcare professional and report it via our Yellow Card scheme."
Licensed Uses and Prevalence
While both Wegovy and Mounjaro are licensed for weight loss prescriptions, Ozempic is approved for diabetes treatment as well as reducing the risk of heart attack and stroke. The MHRA said: "GLP-1s are prescribed for the treatment of type 2 diabetes and, for some products, weight management, and cardiovascular risk reduction in individuals with established cardiovascular disease and a BMI of 27 kg/m2 or more."
Research recently published by University College London estimates that 1.6 million adults in England, Wales and Scotland used GLP-1s, such as semaglutide (Wegovy, Ozempic) and tirzepatide (Mounjaro), between early 2024 and early 2025, to lose weight.
"While GLP-1s are generally considered safe and effective for their authorised uses, like all medications they are not without risk. Those taking GLP-1s should be aware of the symptoms of severe pancreatitis and seek urgent medical attention if they experience them."
Symptoms of Acute Pancreatitis
According to the NHS, the most common symptoms of acute pancreatitis include:
- Suddenly getting severe pain in the centre of your tummy (abdomen)
- Feeling or being sick
- A high temperature of 38C or more (fever)
When to Get Medical Help
The NHS advises: "See a GP immediately if you suddenly develop severe abdominal pain. If this isn't possible, contact NHS 111 for advice."
