There are several causes of pain under the left side of the rib cage: 1, whether it is a kidney disease, such as inflammation of the kidney, tumors or stones, there will be pain behind the bottom of the rib cage. This is the time to perform CT and ultrasound examinations to further confirm the diagnosis and treatment. 2, whether it is the early stage of shingles, the early stage of shingles will appear pain in the nerve distribution area under the rib cage. This is a good time to observe, and if there are clusters of blisters, you should visit a dermatologist for further diagnosis and treatment. 3. whether it is a disease of the spleen. If there is a rupture of the spleen or a secondary enlargement of the spleen, pain under the left side of the rib cage may also occur. 4. Whether it is a disease of the gastrointestinal tract. When enteritis or other tumors of the gastrointestinal tract occur, pain below the left side of the ribs may also occur, and it is important to observe whether there are abnormalities in defecation.