Acute pancreatitis is usually caused by gallstones or drinking too much alcohol, but sometimes no cause can be identified.

Gallstones are small stones that form in your gallbladder. They can sometimes trigger acute pancreatitis if they move out of the gallbladder and block the opening of the pancreas.

It's not fully understood how alcohol causes the pancreas to become swollen (inflamed). One theory is that it causes enzymes inside the pancreas to start digesting it.

Whatever the cause, there is a clear link between alcohol use and acute pancreatitis.

Binge drinking – drinking a lot of alcohol in a short period of time – is also thought to increase your risk of developing acute pancreatitis.

Less common causes of acute pancreatitis include:

• high blood fat levels (hypertriglyceridaemia)
• accidental damage or injury to the pancreas – for example, during a procedure to remove gallstones or examine the pancreas
• a side effect of medicine
• viruses like mumps or measles
• high blood calcium levels (hypercalcaemia)
• the immune system attacking the pancreas (autoimmune pancreatitis)

You're probably more likely to develop severe pancreatitis if you:

• are over 70
• are obese (you have a body mass index (BMI) of 30 or above)
• have 2 or more alcoholic drinks a day
• smoke
• have a family history of pancreatitis