There are several reasons for the vague pain below the left rib cage: first, thoracic diseases, when there is tuberculous pleurisy, or infectious pleurisy, or tumor of the pleura in the thoracic cavity, there will be vague pain below the left rib cage, then CT examination, or X-ray examination should be performed to further confirm the diagnosis, and if necessary, pathological examination. Second, intestinal or intra-abdominal tumors, when the intestinal inflammation or intestinal polyps, or intra-abdominal tumors, intestinal tumors, will also appear vague pain below the left side of the rib cage. In this case, you should go to the general surgery department for a colonoscopy, or CT or MRI to further confirm whether it is caused by inflammation, polyps or tumors, and if necessary, pathological examination. Third, herpes zoster, in the early stages of herpes zoster, may also appear as a vague pain under the left side of the rib cage, and after the latent period, there will be clusters of herpes-like lesions in the nerve zone.