Sciatica is pain that radiates along the sciatic nerve, the longest and thickest nerve in your body. It typically starts in the lower back or buttock and travels down the back of one leg, sometimes reaching the foot. Somewhere between 10% and 40% of people will experience it in their lifetime, making it one of the most common nerve-related pain conditions.
Why the Sciatic Nerve Causes So Much Pain
The sciatic nerve is formed by nerve roots branching out from the lowest part of your spinal cord, roughly at the base of your spine and the top of your pelvis. These roots bundle together and exit the pelvis through a gap deep beneath the muscles of your buttock. From there, the nerve runs down the back of your thigh, eventually splitting into smaller branches that extend through the calf and into the foot.
Because this nerve is so long and passes through so many tight spaces, it’s vulnerable to compression or irritation at several points along its path. When something presses on the nerve or its roots, pain signals fire along the entire length. That’s why a problem in your lower spine can produce pain you feel in your calf or the sole of your foot.
What Sciatica Feels Like
Sciatica is distinctive because the pain follows a specific route. It usually affects only one leg and travels from the lower back or buttock down the back of the thigh. In many cases, it continues below the knee into the calf and foot. The sensation varies: some people describe a sharp, burning, or electric jolt, while others feel a deep ache or persistent tingling. Numbness and muscle weakness in the affected leg are also common, particularly if the nerve compression is significant.
Certain movements tend to make it worse. Bending forward, prolonged standing, coughing, or sneezing can all intensify the pain because these actions increase pressure on the compressed nerve root. Many people find that lying down with the knees slightly bent provides the most relief.
The Most Common Causes
Sciatica is a symptom, not a disease. Something has to be pressing on or irritating the nerve. The two most common culprits are herniated discs and lumbar spinal stenosis.
A herniated disc occurs when the soft center of a spinal disc pushes through its tougher outer layer and presses against a nearby nerve root. This tends to happen suddenly, often after lifting something heavy or twisting awkwardly, and it’s the most frequent cause of sciatica in younger adults.
Lumbar spinal stenosis is a gradual narrowing of the spinal canal in the lower back, which slowly crowds the nerves. It’s more common in people over 60 and tends to develop over months or years rather than overnight. Bone spurs from arthritis are a typical contributor.
Less commonly, sciatica results from a condition called piriformis syndrome, where a small muscle deep in the buttock tightens or spasms around the sciatic nerve. This can mimic sciatica but has some telltale differences: piriformis pain usually starts in the buttock rather than the lower back, is aggravated by hip rotation (sitting for long periods, climbing stairs, getting out of a car), and typically doesn’t extend below the knee. True sciatica from a spinal problem more often radiates all the way to the foot and may come with changes in reflexes or noticeable weakness.
Risk Factors You Can Control
A large analysis of four prospective studies found that several lifestyle factors meaningfully shift your odds of developing sciatica severe enough to require hospitalization. Current smokers had a 33% higher risk compared to nonsmokers, though former smokers who had quit were no longer at increased risk. Obesity raised the risk by 36%, and carrying excess weight specifically around the midsection increased it by 41%.
On the protective side, people who walked or cycled to work reduced their risk by 33%, an effect that held even after accounting for body weight and other exercise habits. Other types of leisure activity didn’t show the same clear benefit, suggesting that consistent, moderate daily movement matters more than occasional intense workouts.
How Sciatica Is Diagnosed
Diagnosis usually starts with a physical exam. One of the most commonly used tests involves lying on your back while a clinician slowly raises your straightened leg. If this reproduces your radiating leg pain, it strongly suggests nerve root irritation. This test is quite sensitive, catching 72% to 97% of disc herniations, though it can produce false positives. A variation where the opposite leg is raised is less sensitive (catching 23% to 42% of cases) but far more specific, meaning that when it’s positive, it’s almost certainly a real nerve root problem.
Imaging like an MRI is typically reserved for cases where symptoms are severe, aren’t improving after several weeks, or where the exam suggests something more serious. Many people have disc bulges on MRI that cause no symptoms at all, so imaging alone doesn’t tell the full story.
Treatment: Conservative Care vs. Surgery
Most sciatica improves without surgery. The standard first approach includes a combination of staying as active as tolerable, physical therapy to strengthen the muscles supporting the spine, and short-term use of anti-inflammatory pain relief. Targeted exercises that take pressure off the nerve root, like certain extension-based movements, often help more than bed rest.
A systematic review comparing conservative treatment to surgery in people with chronic sciatica lasting more than three months found nuanced results. Conservative treatment was associated with greater improvement in leg pain and better mental and physical health scores over time. Surgery, however, provided a more significant reduction in back pain specifically. In practical terms, this means that for many people, patience and structured rehabilitation produce outcomes that are at least comparable to surgery for overall function and quality of life.
Surgery becomes a stronger option when pain is disabling, when there’s progressive muscle weakness, or when conservative care hasn’t helped after several months. The most common procedure for disc-related sciatica is a minimally invasive approach to remove the portion of disc pressing on the nerve. Recovery typically involves a few weeks of limited activity followed by gradual return to normal movement.
When Sciatica Becomes an Emergency
Rarely, pressure on the nerve roots at the base of the spine can cause a condition called cauda equina syndrome, which requires emergency surgery within 24 to 48 hours. The warning signs are distinct from typical sciatica: sudden loss of bladder or bowel control, inability to urinate, numbness in the groin or inner thighs (sometimes called “saddle” numbness because it affects the area that would contact a saddle), and rapidly worsening weakness in both legs. If you experience any combination of these symptoms alongside back or leg pain, go to an emergency room immediately. This is one of the few true surgical emergencies in spine care, and delays can lead to permanent nerve damage.