Sciatica: Why Does Pain Shoot Down My Leg?

Sciatica is pain that starts in the lower back or buttock and travels down one leg, often below the knee. It usually reflects irritation or pressure on a nerve root in the lower spine, and a herniated disk is one common cause. Most episodes are not dangerous, but new leg weakness, numbness in the groin area, or loss of bladder or bowel control needs emergency care. This article covers causes, symptoms, self-care, and warning signs.

What sciatica is and why pain shoots down the leg

Sciatica describes pain along the path of the sciatic nerve. According to MedlinePlus, this nerve runs from the lower back through the hips and buttocks and down each leg. When something irritates or compresses the nerve or the roots that form it, pain can follow that route.

Sciatica is a symptom, not a diagnosis. The leg pain is often described as sharp, burning, or electric, and it commonly affects one side. Many people also notice tingling, numbness, or weakness in the leg or foot. Several factors can contribute, and the exact mechanism in any one person is not always clear. Pressure on the nerve root and local inflammation around it are both thought to play a part.

What sciatica can feel like

Symptoms vary from person to person. Common patterns include:

• Pain that starts in the lower back or buttock and travels down the back or side of one leg, sometimes to the foot.
• Pain that gets worse with sitting, coughing, sneezing, or bending forward.
• Tingling, "pins and needles," or numbness in the leg or foot.
• Weakness in the leg, which may show up as difficulty lifting the front of the foot or rising from a chair.

Leg pain can come from other sources. If the pain is mainly in the calf with swelling or warmth, see our article on early signs of a blood clot in the leg. Cramping at night has its own explanations, covered in the article on leg cramps at night.

Common causes of sciatica

Sciatica can arise from several conditions in or near the lower spine. MedlinePlus describes a herniated disk as a problem in which part of the cushion between spinal bones pushes out and may press on nearby nerves. A herniated disk is a common cause of sciatica, though not the only one.

• Herniated or bulging disk: the disk material may press on or irritate a nerve root.
• Spinal stenosis: narrowing of the spinal canal or the openings where nerves exit, which is more often seen with age-related changes.
• Spondylolisthesis: one vertebra slipping forward over another and narrowing the space for a nerve.
• Piriformis syndrome: a muscle deep in the buttock may irritate the nerve in some people. Clinicians sometimes debate how often this is the true cause.
• Injury or trauma: a fall or accident can affect the spine or the nerve.

Much less common causes include tumors, infection, and bleeding near the spine. One symptom alone does not establish any of these, but they are part of why certain warning signs, listed below, deserve prompt attention.

General low back pain has its own wide list of causes, which we cover in the article on causes of lower back pain. Here the focus is pain that travels into the leg.

Who is more likely to develop it

Sciatica can affect people of many ages, but it is often reported in adults in middle age and beyond, when disk and spine changes become more common. Factors associated with a higher chance include older age, prior back problems, physically demanding work, prolonged sitting, and smoking. Excess body weight and diabetes have also been linked with nerve problems in general. These associations are general patterns, and having a risk factor does not mean you will develop sciatica.

How clinicians evaluate leg pain from the back

Clinicians combine your history, a physical examination, and sometimes imaging. They may ask where the pain travels, what makes it better or worse, and whether you have weakness, numbness, or changes in bladder or bowel function. During the exam they may check reflexes, muscle strength, sensation, and how the pain responds to leg-raising movements.

Imaging such as MRI is not needed for everyone. Guidelines for acute low back pain, which a PubMed Central paper on physicians' initial management compared with evidence-based guidelines examines, generally advise against routine imaging at the start. It is often considered when symptoms are severe, keep getting worse, do not improve with initial care, or when a clinician suspects a serious cause. Because X-rays do not show nerves or disks well, a clinician may choose a different test depending on what they suspect. Nerve conduction studies are sometimes used when the diagnosis is unclear. MedlinePlus on peripheral nerve disorders gives background on how nerve problems are assessed more broadly.

What may help at home

Many people improve over weeks with conservative care, though recovery varies and some people have symptoms that last longer. General approaches that clinicians often discuss include:

• Staying gently active. Short walks and light movement are often suggested over prolonged bed rest, which can stiffen the back.
• Heat or cold. Some people find a cold pack helps early on and heat helps later. Protect the skin with a cloth.
• Changing positions. Breaking up long periods of sitting and finding a comfortable position for sleep, such as lying on the side with a pillow between the knees, may ease pressure.
• Over-the-counter pain relievers. Options such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) are commonly used. NSAID labels carry a boxed warning for heart attack, stroke, and stomach bleeding, and acetaminophen can harm the liver above the labeled daily maximum, so follow the label and check with a pharmacist. Avoid taking two products that contain the same ingredient, since many cold and combination products include acetaminophen or an anti-inflammatory. Ask a pharmacist or clinician which is appropriate for you, especially if you have kidney disease, stomach ulcers, liver disease, heart disease, are pregnant, or take blood thinners.
• Gentle stretching and physical therapy. A physical therapist can tailor exercises to your situation.

Tell your clinician about any treatment you are trying so they can decide whether it fits your situation.

Treatments a clinician may discuss

Staying active, physical therapy, and other non-drug approaches are usually discussed first. If symptoms persist or are severe, a clinician may discuss additional options. These can include prescription medicines, injections near the affected nerve root, and, in selected cases, surgery. Evidence for medicines and injections is mixed. For example, researchers have registered randomized trials examining oral steroids for acute sciatica (the OASIS trial protocol), duloxetine for chronic sciatica (the DREAM trial protocol), and pregabalin added to usual care (the PRECISE trial protocol). Those links describe study designs, not proven results, so they should not be read as a recommendation for any drug.

Medicines used for nerve pain can have important side effects. Duloxetine's prescribing label carries a boxed warning about suicidal thoughts and behavior in children, adolescents, and young adults. Pregabalin can cause drowsiness and dizziness, and oral steroids have their own risks, so a prescriber should weigh these for you. Do not start, stop, or change the timing or dose of a prescription on your own; ask the prescriber or pharmacist.

Surgery is generally considered for people with serious or progressive nerve problems, or whose pain remains disabling despite other care, as MedlinePlus on herniated disk outlines. A surgeon can explain the benefits and risks for your particular spine findings.

Warning signs that need urgent attention

Most sciatica is not an emergency. A small number of people develop pressure on the bundle of nerves at the base of the spine, sometimes called cauda equina syndrome. This can cause lasting harm to bladder, bowel, sexual, and leg function, and it requires emergency evaluation. Warning features include:

• New trouble urinating, loss of bladder control, or loss of bowel control.
• Numbness in the groin, genital, or inner thigh area, sometimes described as a saddle distribution.
• Weakness or numbness in both legs, weakness that is quickly getting worse, or being unable to stand or walk.

New weakness in one foot, such as tripping or trouble lifting the front of the foot, is a nerve deficit that needs prompt evaluation. Sudden weakness on one side of the body, a drooping face, or trouble speaking is a possible stroke rather than sciatica, and calls for 911.

Leg pain can also come from problems in the blood vessels that are easy to mistake for sciatica. A swollen, warm, red, painful calf may suggest a deep vein clot, and chest pain or shortness of breath alongside it can suggest the clot has traveled to the lungs. A leg that suddenly turns cold, pale, blue, or numb with severe pain may suggest a blocked artery. Both need emergency care.

Back or leg pain after a serious fall, car accident, or other major injury, especially with weakness, numbness, or inability to walk, needs emergency evaluation because fracture or spinal injury is possible. After a minor injury with mild pain, a prompt clinician visit is reasonable. Back pain together with fever, unexplained weight loss, a history of cancer, or a weakened immune system should also be assessed promptly because infection or tumor is a possibility. These are much less common than the everyday causes described above.

Also seek care if pain is severe and not controlled with the measures above, or if it has not improved after several weeks. Your clinician can decide on the right timing for further evaluation. For background on back pain more broadly, see MedlinePlus on back pain.

Living with sciatica and preventing flare-ups

Staying active, keeping core and leg muscles conditioned, using safe lifting technique, and avoiding long stretches of sitting may reduce the chance of repeat episodes, though no approach prevents sciatica for everyone. If you smoke, your clinician can discuss support for quitting, since smoking has been associated with back problems. If the pain returns often, a physical therapist or clinician can look for patterns in posture, work tasks, or movement that may be contributing.

When to Seek Medical Care