Pancreatitis: Inflammation of the pancreas. Of the many causes of pancreatitis, the most common are alcohol consumption and gallstones. Other causes include medications (azathioprine, estrogen, thiazides, metronidazole, valproic acid, and tetracycline), trauma, abdominal surgery, abnormalities of the pancreas and intestine, and infections such as mumps. Acute pancreatitis usually begins with pain in the upper abdomen that may last for a few days. The pain may be sudden and intense, or it may begin as a mild pain that is aggravated by eating and slowly grows worse. The abdomen may be very tender. Other symptoms may include nausea, vomiting, and fever. The patient often feels and looks very sick. Chronic pancreatitis usually follows many years of alcohol abuse and may cause pain; malabsorption of food, leading to weight loss; and diabetes, if the insulin-producing cells of the pancreas (islet cells) are damaged.