Sciatica is pain that travels along the sciatic nerve, the longest nerve in your body. It runs from your lower back through your buttocks and down each leg, and when something irritates or compresses it, you can feel pain, numbness, or tingling anywhere along that path. Most people feel it on only one side, and it ranges from a dull ache to a sharp, burning sensation that can make standing or walking difficult.
The Nerve Behind the Pain
The sciatic nerve forms from a bundle of nerve roots branching off the lower spine, specifically from the lumbar and sacral vertebrae (L4 through S3). These roots merge into a single thick nerve that exits the pelvis through an opening near the piriformis muscle deep in your buttock. From there it travels down the back of your thigh, and just above the back of your knee it splits into two branches that continue into your lower leg, foot, and toes.
Because this nerve is so long and passes through so many structures, there are multiple points where it can get pinched, squeezed, or inflamed. That’s why sciatica isn’t a diagnosis on its own. It’s a symptom pattern that can come from several different underlying problems.
What Sciatica Feels Like
The hallmark of sciatica is pain that radiates from your lower back or buttock down the back of one leg. People commonly describe it as a burning or electric shock sensation. It often gets worse when you cough, sneeze, or bend forward, and raising the affected leg while lying on your back can intensify it.
Beyond pain, sciatica can produce numbness, a pins-and-needles tingling, or a feeling that part of your leg has “gone to sleep.” These sensations can show up in your buttock, thigh, calf, foot, or toes. In more severe cases, you may notice weakness in the affected leg, making it harder to push off while walking or lift your foot normally.
Common Causes
Most sciatica originates in the spine. A herniated disc is the most frequent culprit: the soft interior of a spinal disc pushes out and presses against a nearby nerve root. But the nerve compression doesn’t have to come from a disc. Several spinal conditions can produce the same effect:
- Bulging disc: the disc shifts outward without fully rupturing, narrowing the space around the nerve.
- Spinal stenosis: the spinal canal gradually narrows, usually from age-related changes, and crowds the nerves.
- Bone spurs: bony overgrowths on the vertebrae encroach on the nerve openings.
- Spondylolisthesis: one vertebra slips forward over the one below it, pinching the nerve root.
The process involves both physical compression and inflammation. When a disc herniates, the material that leaks out triggers an inflammatory response around the nerve root, which amplifies the pain beyond what pressure alone would cause. This is why sciatica can feel so intense even when imaging shows only a small disc bulge.
Piriformis Syndrome
Not all sciatic pain starts in the spine. The piriformis is a small muscle deep in each buttock that sits right next to the sciatic nerve. If this muscle spasms, tightens, or swells, it can compress the nerve after it has already exited the spine. Piriformis syndrome tends to cause pain concentrated in the buttock and hip rather than shooting all the way down to the foot. Sitting for long periods often makes it worse, while spinal sciatica is more likely to flare when you raise your leg while lying down.
The distinction matters because piriformis syndrome doesn’t involve the spine at all, which means spinal imaging may look completely normal. A clinician can often tell the two apart by moving your hips and legs in specific positions. If the pain stays in the buttock and hip area, piriformis syndrome is more likely. If it travels into the lower leg or foot, a spinal cause is the usual suspect.
How Sciatica Is Identified
Diagnosis typically starts with a physical exam. One of the most well-known tests is the straight leg raise: you lie on your back while a clinician lifts your affected leg with your knee straight. If this reproduces your typical leg or back pain before your leg reaches about 60 degrees, it suggests a disc-related nerve compression. The test is a useful screening tool, though its accuracy varies. In people over 60, for instance, its sensitivity drops to around 33%, meaning it misses a significant number of cases in that age group.
If symptoms are severe, persistent, or accompanied by weakness, imaging enters the picture. An MRI can show whether a disc herniation, stenosis, or another structural problem is responsible. But imaging is usually reserved for cases where the diagnosis is unclear or symptoms aren’t improving, because many people have disc bulges on MRI without any pain at all.
What Recovery Looks Like
Most sciatica improves within a few weeks to a few months without surgery. The early phase is about managing pain and staying as active as you can without making symptoms significantly worse. Gentle walking, stretching, and movements that don’t load the spine heavily tend to be more helpful than strict bed rest. Prolonged inactivity can actually slow recovery by weakening the muscles that support your back.
Physical therapy plays a central role for persistent cases. A therapist can guide you through exercises that take pressure off the nerve, strengthen the muscles around your spine, and improve the flexibility of your hips and hamstrings. Core stability work is particularly important because the deep muscles of your trunk act like a natural brace for your lower spine, reducing the load on discs and joints.
For sciatica that doesn’t respond to conservative care over several months, procedures like epidural steroid injections can reduce inflammation around the nerve root. Surgery becomes an option when there’s significant weakness, progressive nerve damage, or pain that remains disabling despite other treatments. The most common procedure removes the portion of disc material pressing on the nerve, and most people experience substantial relief afterward.
Reducing Your Risk
You can’t eliminate every risk factor for sciatica, especially age-related disc changes, but certain habits lower the odds of an episode or a recurrence. Lifting with your legs rather than rounding your back protects the discs from the kind of sudden pressure that causes herniations. If you sit for long stretches at work, standing up and moving every 30 to 45 minutes helps keep the muscles around your spine from stiffening. A chair that supports the natural curve of your lower back reduces sustained pressure on your discs.
Regular exercise, especially anything that builds core strength, is one of the most effective long-term strategies. Swimming, walking, yoga, and pilates all fit the bill. Maintaining a healthy weight also matters because extra body weight increases the compressive forces on your lumbar discs with every step you take.
When Sciatica Becomes an Emergency
Rarely, the nerve compression behind sciatica can escalate into a condition called cauda equina syndrome, where the bundle of nerves at the base of the spine becomes severely compressed. This is a surgical emergency. The warning signs include sudden loss of bladder or bowel control, numbness in the groin and inner thighs (sometimes called saddle numbness because it affects the area that would contact a saddle), sexual dysfunction, and progressive weakness in both legs. If you experience any combination of these symptoms, you need emergency medical attention. Permanent nerve damage can result if the pressure isn’t relieved quickly, typically within hours.