Pancreatitis is inflammation in the pancreas. The pancreas is a long, flat gland that sits tucked behind the stomach in the upper abdomen. The pancreas produces enzymes that help digestion and hormones that help regulate the way your body processes sugar (glucose). Pancreatitis can occur as acute pancreatitis — meaning it appears suddenly and lasts for days. Or pancreatitis can occur as chronic pancreatitis, which is pancreatitis that occurs over many years. Mild cases of pancreatitis may go away without treatment, but severe cases can cause life-threatening complications.