Understanding New and Severe Abdominal Pain

Your abdominal pain may be from a serious infection, and you should be evaluated by your doctor today.

When you have pain in the upper abdomen with fever, some of the most concerning possible explanations are pneumonia, fluid surrounding the lung (pleural effusion), pancreatitis, or an abscess in the spleen or nearby in the abdomen.

Several viral infections can cause enlargement of your spleen, and this can result in abdominal pain in the left upper abdomen. The most common infection that causes the spleen to enlarge is the viral infection mononucleosis, and this infection usually also causes an extremely sore throat.

The upper abdomen is a common location for the skin rash of "shingles" (varicella zoster infection, also called herpes zoster). This infection can cause pain and a low-grade fever.

A common viral infection in the stomach ("gastroenteritis") can also cause pain in this area.