Back pain is pain felt in the back. Episodes of back pain may be acute, sub-acute, or chronic depending on the duration. The pain may be characterized as a dull ache, shooting or piercing pain, or a burning sensation. The pain may radiate into the arms and hands as well as the legs or feet, and may include paresthesia (tingling with no apparent cause),[1] weakness or numbness in the legs and arms. The anatomic classification of back pain follows the segments of the spine: neck pain (cervical), middle back pain (thoracic), lower back pain (lumbar) or coccydynia (tailbone or sacral pain) with the lumbar vertebrae area most common for pain.
 
The pain may originate from the muscles, nerves, bones, joints or other structures in the vertebral column (spine). Internal structures such as the gallbladder and pancreas may also cause referred pain in the back.
 
 Back pain is common with about nine out of ten adults experiencing it at some point in their life, and five out of ten working adults having it every year. However, it is rare for it to be permanently disabling, and in most cases of herniated disks and stenosis, rest, injections or surgery have similar general pain resolution outcomes on average after one year. In the United States, acute low back pain is the fifth most common reason for physician visits and causes 40% of missed days off work. Additionally, it is the single leading cause of disability worldwide
 
 Back pain does not usually require immediate medical intervention. The vast majority of episodes of back pain are self-limiting and non-progressive. Most back pain syndromes are due to inflammation, especially in the acute phase, which typically lasts from two weeks to three months
 
Back pain can be a sign of a serious medical problem, although this is not most frequently the underlying cause.    Typical warning signs of a potentially life-threatening problem are bowel and/or bladder incontinence or progressive weakness in the legs.
 
    Severe back pain (such as pain that is bad enough to interrupt sleep) that occurs with other signs of severe illness (e.g. fever, unexplained weight loss) may also indicate a serious underlying medical condition. Back pain that occurs after a trauma, such as a car accident or fall, may indicate a bone fracture or other injury.Back pain in individuals with medical conditions that put them at high risk for a spinal fracture, such as osteoporosis or multiple myeloma, also warrants prompt medical attention.Back pain in individuals with a history of cancer (especially cancers known to spread to the spine like breast, lung and prostate cancer) should be evaluated to rule out metastatic disease of the spine.
 
A few observational studies suggest that two conditions to which back pain is often attributed, lumbar disc herniation and degenerative disc disease, may not be more prevalent among those in pain than among the general population, and that the mechanisms by which these conditions might cause pain are not known. Other studies suggest that for as many as 85% of cases, no physiological cause can be shown.A few studies suggest that psychosocial factors such as on-the-job stress and dysfunctional family relationships may correlate more closely with back pain than structural abnormalities revealed in X-rays and other medical imaging scans.
 
Sciatica is a medical condition of pain going down the leg from the lower back. This pain may go down the back, outside, or front of the leg. Typically, symptoms are only on one side of the body. Certain causes, however, may result in pain on both sides. Lower back pain is sometimes but not always present. Weakness or numbness may occur in various parts of the leg and foot.
 
About 90% of the time sciatica is due to a spinal disc herniation pressing on one of the lumbar or sacral nerve roots. Other problems that may result in sciatica include spondylolisthesis, spinal stenosis, piriformis syndrome, pelvic tumors, and compression by a baby's head during pregnancy. The straight-leg-raising test is often helpful in diagnosis. The test is positive if, when the leg is raised while a person is lying on their back, pain shoots below the knee. In most cases medical imaging is not needed. Exceptions to this are when bowel or bladder function is affected, there is significant loss of feeling or weakness, symptoms are long standing, or there is a concern of a tumor or infection. Conditions that may present similarly are diseases of the hip and early herpes zoster before the rash appears.