Sciatica is pain that travels along the sciatic nerve, the longest nerve in your body. It typically starts in the lower back and shoots down through the buttock and the back of one leg, sometimes reaching all the way to the foot. Most people recover within a few weeks to months, but the pain can range from a mild ache to a sharp, burning sensation that makes standing or sitting difficult.
Where the Sciatic Nerve Runs
The sciatic nerve forms from a bundle of nerve roots near the base of your spine, specifically from the fourth lumbar vertebra down to the third sacral vertebra (L4 through S3). These roots merge into a single thick nerve that passes through the pelvis and deep into the buttock, then runs down the back of each thigh. Near the back of the knee, it splits into two branches that continue into the lower leg and foot. Because this nerve is so long and touches so many areas, a problem at any point along its path can send pain radiating far from the actual source.
What Causes It
The most common cause is a herniated disc in the lower spine. Spinal discs act as cushions between vertebrae, and when the soft inner material pushes outward, it can press directly on a nearby nerve root. But the damage isn’t purely mechanical. Herniated disc material also releases inflammatory chemicals that irritate the nerve, which is why even small herniations sometimes produce severe pain. This combination of physical pressure and chemical inflammation explains why sciatica can flare unpredictably and why anti-inflammatory treatments sometimes help even when the disc itself hasn’t changed.
Other causes include spinal stenosis (a narrowing of the canal the nerve passes through), bone spurs from arthritis, and piriformis syndrome, where a muscle deep in the buttock tightens and compresses the nerve. Pregnancy can trigger sciatica as well, since the expanding uterus shifts weight and posture in ways that pressure the lower spine. In rarer cases, tumors or infections near the spine are responsible.
What Sciatica Feels Like
The hallmark of sciatica is pain that follows a path. It doesn’t stay in one spot the way a muscle strain does. You might feel it in your lower back, buttock, the back of your thigh, your calf, or some combination of all of these. The sensation is often described as a burning feeling or an electric shock that shoots down the leg. It tends to get worse when you cough, sneeze, bend forward, or lift your legs while lying on your back.
Beyond pain, sciatica can cause numbness, tingling, or a pins-and-needles sensation in the affected leg. Some people notice weakness, like a foot that feels heavy or a leg that gives out unexpectedly. These nerve-related symptoms distinguish sciatica from ordinary back pain. Sciatica almost always affects only one side of the body at a time.
How It’s Diagnosed
Doctors can often identify sciatica with a physical exam before ordering any imaging. One of the most useful tests is the straight leg raise: you lie flat on your back while the examiner slowly lifts one leg. The test is considered positive if raising the leg between 30 and 70 degrees reproduces your shooting pain below the knee. This test is highly sensitive, catching about 91% of true sciatica cases. However, it’s not very specific, meaning it can also be positive in people without true nerve root compression. Pain that stays only in the lower back without radiating past the knee, or general tightness in the hamstrings, doesn’t count as a positive result.
If symptoms are severe, persistent, or include muscle weakness, your doctor will likely order an MRI to see exactly where and how the nerve is being compressed. This imaging helps distinguish a herniated disc from stenosis or other structural problems and guides decisions about whether you need more aggressive treatment.
Treatment and Recovery
Most sciatica improves with conservative care over several weeks. The first-line approach typically combines over-the-counter anti-inflammatory pain relievers, gentle movement, and avoiding positions that aggravate the nerve. Strict bed rest is no longer recommended because prolonged inactivity can actually slow recovery. Short walks and light stretching tend to help more than lying still.
Physical therapy is a common next step. Exercises that combine core strengthening with neural mobilization (gentle movements designed to help the nerve glide more freely through surrounding tissue) have shown some of the largest reductions in leg pain in clinical studies, though the overall evidence for any single non-surgical approach remains limited. What works varies from person to person, so treatment often involves some trial and adjustment. Epidural steroid injections are sometimes used when pain is too severe for physical therapy alone, delivering anti-inflammatory medication directly near the irritated nerve root.
Surgery becomes an option when pain persists for months despite conservative treatment, or when nerve compression is causing progressive weakness or loss of function. The most common procedure removes the portion of disc or bone that’s pressing on the nerve. Recovery from this surgery typically takes a few weeks before you can return to daily activities, with full recovery over several months.
Red Flags That Need Emergency Care
A rare but serious complication called cauda equina syndrome occurs when the bundle of nerves at the base of the spinal cord gets compressed all at once. This requires emergency surgery, ideally within 24 to 48 hours. The warning signs are distinct from typical sciatica: sudden numbness or tingling in the inner thighs, buttocks, or groin (sometimes called saddle numbness), loss of bladder or bowel control, inability to urinate even when your bladder feels full, and rapidly worsening weakness in one or both legs. If you experience any combination of these symptoms alongside back or leg pain, go to the emergency room immediately. Without prompt treatment, nerve damage from cauda equina syndrome can become permanent.