A health alert has been raised in the UK as hundreds of people using injections for weight loss and diabetes have reported issues linked to the pancreas.

Some cases of pancreatitis, reportedly connected to GLP-1 receptor agonist drugs (glucagon-like peptide-1), have even resulted in fatalities.

Acute pancreatitis is a sudden inflammation of the pancreas, a gland located behind the stomach that plays a vital role in digestion. The condition often requires hospitalization. Symptoms include severe abdominal pain, nausea, and fever.

GLP-1 drug leaflets list pancreatitis as an “uncommon” side effect, affecting about one in 100 patients. To date, the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) Yellow Card scheme has received nearly 400 reports of acute pancreatitis in patients treated with Mounjaro, Wegovy, Ozempic, and liraglutide, with almost half (181 cases) linked to tirzepatide (Mounjaro).

Rise in cases during 2025
Since the beginning of the year, there have been 22 reports of acute pancreatitis linked to semaglutide (Ozempic and Wegovy) and 101 linked to tirzepatide (Mounjaro).

An MHRA spokesperson stated:
“Alongside increased usage, we are seeing a rise in Yellow Card reports that mention GLP-1 medications and acute pancreatitis.”

Due to the seriousness of the condition, the MHRA announced it is investigating whether genetic factors may predispose individuals to pancreatitis. The agency urges anyone hospitalized with suspected pancreatitis related to these drugs to report it through the Yellow Card scheme. Healthcare professionals are also encouraged to report cases on behalf of their patients.

Studies suggest that adverse drug reactions account for one in six hospital admissions.

Drug makers respond
Dr. Alison Cave, MHRA Chief Safety Officer, said:
“Evidence shows that almost one-third of adverse drug reactions could be prevented through genetic testing. It’s estimated that adverse reactions cost the NHS over £2.2 billion a year in hospital admissions alone.”

A spokesperson for Lilly, maker of Mounjaro, commented:
*”Patient safety is our top priority. We take every safety report seriously and actively monitor, assess, and report safety data for all our medicines. Adverse events should be reported through the Yellow Card scheme, though they may also be related to other factors, such as pre-existing conditions.

The Mounjaro (tirzepatide) product information warns that inflammation of the pancreas (acute pancreatitis) is an uncommon side effect (may affect up to 1 in 100 people). Patients are advised to consult their doctor before use if they have a history of pancreatitis.”*

A spokesperson for Novo Nordisk UK, manufacturer of Ozempic and Wegovy, added:
*”Patient safety is of utmost importance to us. As with any medication, side effects may occur and vary from person to person.

The known risks and benefits of GLP-1 medications are outlined in the product’s summary of characteristics. We recommend that these medicines be used only for approved indications and under the supervision of a healthcare professional, who can also advise on potential side effects.”