What is sciatica?

What is sciatica, exactly?

Sciatica is not a condition on its own—it’s a set of symptoms caused by something irritating or compressing the sciatic nerve. The sciatic nerve is the longest nerve in the body. It starts in your lower back, runs through your hips and buttocks, and branches all the way down each leg.

When the nerve gets pinched or inflamed anywhere along that path, you feel pain, numbness, or weakness that radiates down from the lower back into the leg—often only on one side.

The most common causes

According to the NIH and Mayo Clinic, sciatica is most frequently triggered by:

• Herniated (slipped) disc. The soft inner part of a spinal disc bulges out and presses on a nerve root. Accounts for the overwhelming majority of cases.
• Spinal stenosis. A gradual narrowing of the spinal canal, more common with age, that puts pressure on the nerves.
• Bone spurs on the spine caused by arthritis.
• Piriformis syndrome. When the piriformis muscle deep in the buttock tightens or spasms and compresses the nerve beneath it.
• Pregnancy, which can shift weight and increase pressure on the lower back.
• Rarer causes: cysts, tumors, or other lesions growing near the nerve.

How it usually feels

Sciatica has a distinctive feel that most people recognize once they have it. The classic signs:

• Pain that radiates from the lower back through the buttock and down the back of one leg.
• A burning, tingling, or “electric” sensation along the nerve’s path.
• Numbness or weakness in the affected leg or foot.
• Pain that gets worse when sitting, coughing, sneezing, or straining.
• Relief when lying flat or walking slowly.

Sciatica pain can feel like a dull ache or a sharp, “shooting” sensation. It almost always affects only one side of the body.

The good news about recovery

The most effective first-line approach recommended by physicians is physical therapy, because it’s active, educational, and restores function rather than masking symptoms. Medications and injections can play a supporting role for severe pain, but rest alone is generally not recommended—gentle movement is.

Your next step

Knowing what sciatica is and what causes it is only the beginning. The real question is what to do about it every day.