Sciatica is a symptom of a problem with the sciatic nerve, the largest nerve in the body.

It controls muscles in the back of your knee and lower leg and provides feeling to the back of your thigh, part of your lower leg, and the sole of your foot. When you have sciatica, you have pain, weakness, numbness, or tingling. It can start in the lower back and extend down your leg to your calf, foot, or even your toes.

Causes of sciatica include: a ruptured intervertebral disk; narrowing of the spinal canal that puts pressure on the nerve, called spinal stenosis; an injury such as a pelvic fracture. In many cases no cause can be found.

Common symptoms of sciatica include: pain in the rear or leg that is worse when sitting; burning or tingling down the leg; weakness, numbness, or difficulty moving the leg or foot; a constant pain on one side of the rear; a shooting pain that makes it difficult to stand up

Sciatica usually affects only one side of the lower body. Often, the pain extends from the lower back all the way through the back of the thigh and down through the leg. Depending on where the sciatic nerve is affected, the pain may also extend to the foot or toes.

For some people, the pain from sciatica can be severe and debilitating. For others, the sciatica pain might be infrequent and irritating, but has the potential to get worse.

Additional common causes of sciatica include: lumbar spinal stenosis (narrowing of the spinal canal in the lower back); degenerative disc disease (breakdown of discs, which act as cushions between the vertebrae); spondylolisthesis (a condition in which one vertebra slips forward over another one); pregnancy.

Other things that may make your back pain worse include being overweight, not exercising regularly, wearing high heels, or sleeping on a mattress that is too soft.