Sciatica refers to pain that travels along the path of the sciatic nerve. The sciatic nerve travels from the buttocks and down each leg.
Sciatica most often happens when a herniated disk or an overgrowth of bone puts pressure on the lumbar spine nerve roots. This happens "upstream" from the sciatic nerve. This causes inflammation, pain and often some numbness in the affected leg.
Although the pain associated with sciatica can be serious, those cases that are caused by a herniated disk can clear up with treatment in a few weeks to months. People who have severe sciatica and serious leg weakness or bowel or bladder changes might need surgery.

The sciatic nerve is the confluence of nerve roots from the lower back. The sciatic nerve extends from the buttocks down each leg.
Sciatica pain can be almost anywhere along the nerve pathway. It's especially likely to follow a path from the low back to the buttock and the back of a thigh and calf.
The pain can vary from a mild ache to a sharp, burning pain. Sometimes it feels like a jolt or electric shock. It can be worse when coughing or sneezing or sitting a long time. Usually, sciatica affects only one side of the body.
Some people also have numbness, tingling, or muscle weakness in the leg or foot. One part of the leg can be in pain, while another part can feel numb.
Mild sciatica usually goes away over time. Call your primary care professional if self-care measures don't ease symptoms. Also call if pain lasts longer than a week, is severe or gets worse. Get immediate medical care for:
Sciatica occurs when the nerve roots to the sciatic nerve become pinched. The cause is usually a herniated disk in the spine or an overgrowth of bone, sometimes called bone spurs, on the spinal bones. More rarely, a tumor can put pressure on the nerve.

The rubbery disks that lie between the bones in the spine have a soft center, called a nucleus. The nucleus is surrounded by a tougher exterior, called the annulus. A herniated disk happens when part of the soft center pushes out through a tear in the tough outer layer. If the herniated disk presses on a nerve, it may cause symptoms.
Risk factors for sciatica include:
Most people recover fully from sciatica caused by herniated disks, often without treatment. But sciatica can damage nerves. Seek immediate medical attention for:
It's not always possible to prevent sciatica, and the condition can come back. To protect your back: