Sciatica is a pain in the leg due to irritation of the sciatic nerve. The pain generally goes from the back of the thigh to the back of the calf, and may also extend upward to the hip and down to the foot. In addition to pain, there may be numbness and difficulty moving or controlling the leg. Typically, the symptoms are only felt on one side.

The sciatic nerve exits the spinal column between the lowest lumbar vertebral body (L5) and first level of the sacrum (S1). It supplies sensation to the posterior thigh and buttock, knee flexors, and foot muscles. When this nerve is compressed, inflamed, or irritated anywhere along its length, pain may result.

Because of the many conditions that can compress nerve roots and cause sciatica, treatment options often differ from patient to patient. Treatment of the underlying cause of the compression is often the most effective course.

Imaging methods such as MRI neurography may help diagnosis and treatment of sciatica. MR neurography is a modified MRI technique using MRI software to provide better pictures of the spinal nerves and the effect of compression on these nerves. MR neurography may help diagnose piriformis syndrome which is another cause of sciatica that does not involve disc herniation. MR neurography is considered experimental and is not covered by insurances.

Most cases of sciatica can be effectively treated by physical therapy or massage therapy and appropriate changes in behavior and environment (for example cushioning, chair and desk height, exercise, stretching). Other conservative treatment options include anti-inflammatory medications (i.e. NSAIDs or oral steroids), pain medications, and epidural steroid injections (however the latter carries the risk of possible side effects and complications from the needle puncture and medications used). "Alternative" and "complementary" treatments include chiropractic manipulation (although there is no scientific consensus for chiropractic's effectiveness) and somatics. Acupuncture has no effect beyond placebo in treating sciatica.