It is not uncommon to have back pain for no apparent reason. A minor injury may have occurred without your knowledge. Poor posture or improper movement over a period of time may cause back pain without a clear reason.

Back pain may be caused by other health problems.

• Diseases that may weaken the spine include osteoarthritis, osteoporosis, and Paget's disease. These diseases are more common in older adults. In rare cases, tumors or infections can develop in or around the spine.
• Some medical conditions, such as endometriosis or gallstones, can cause pain to spread to the back from other parts of the body (referred pain). Many health problems that can cause back pain have nothing to do with the bones, joints, muscles, or ligaments of the back.
• Shingles (herpes zoster) causes back pain that is followed by a rash of chickenpoxlike blisters in a band around the one side of the chest, abdomen, or face. The pain may start before the rash develops and continue while the rash is present, and after the rash has cleared up.
• Back pain that spreads to one buttock and down the back of the leg into a foot (sciatica) may be caused by pressure on a nerve (nerve root compression). This type of problem may occur after sneezing, coughing, or straining.

Unexplained fever with back or flank pain may be a symptom of an infection of the spine, bladder, or kidney. For more information about back pain and urinary problems, see the topic Urinary Problems, Age 12 and Older.