Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Back Pain

What Is It?

Back pain can be a symptom of many different illnesses and conditions. The main cause of the pain can be a problem with the back itself or by a problem in another part of the body. In many cases, doctors can't find a cause for the pain. When a cause is found, common explanations include:

• Stress or injury involving the back muscles, including back sprain or strain; chronic overload of back muscles caused by obesity; and short term overload of back muscles caused by any unusual stress, such as lifting or pregnancy

• Disease or injury involving the back bones (vertebrae), including fracture from an accident or as a result of the bone-thinning disease osteoporosis

• Degenerative arthritis, which is caused by wear and tear

• Disease or injury involving the spinal nerves, including nerve injury caused by a protruding disk (a fibrous cushion between vertebrae) or spinal stenosis (a narrowing of the spinal canal)

• Kidney stones or a kidney infection (pyelonephritis)

Rarer causes include:

• Inflammatory arthritis, including ankylosing spondylitis and related conditions

• A spinal tumor or a cancer that has spread (metastasized) to the spine from elsewhere in the body

• Infection, which may be in the disk space, bone (osteomyelitis), abdomen, pelvis or bloodstream