What Is Sciatica and Why Does It Run Down My Leg?

Key Takeaways

• Sciatica describes pain that starts in the lower back or buttock and travels along the sciatic nerve into the leg, so it is a symptom pattern and not a diagnosis.
• Leg symptoms appear because a nerve root in the lower spine is compressed or inflamed, and the body maps that irritation across everything that nerve supplies.
• Most people improve over weeks to months with movement, guided exercise and time, and scans are not needed for everyone.
• Bladder or bowel changes, numbness around the saddle area or worsening leg weakness need urgent medical attention.

The pain often arrives without much warning. One moment you are lifting a box or standing up from the couch, the next there is a hot, electric line running from your lower back through your buttock and down the back of your leg. Your back might barely ache, yet your calf feels like it is on fire. So what is sciatica, and why does it travel so far from where the problem sits?

Sciatica is pain that follows the path of the sciatic nerve, the longest nerve in the body. It is one of the more distinctive presentations of a very common problem: the Australian Institute of Health and Welfare estimated that around 4.0 million Australians, or 16% of the population, were living with back problems in 2022.

The leg symptoms usually make sense once you understand the anatomy, and most cases settle without surgery. Assessment still matters because similar leg pain can come from several sources and treatment changes depending on which one is driving it. A tailored physiotherapy program can identify which structures are sensitive and what movement your body is ready for.

Nerve pain feels alarming because it is sharp, unfamiliar and hard to ignore, yet the intensity does not reliably reflect the amount of damage.

What Sciatica Actually Is

Sciatica describes where symptoms travel, not why they started. Two people with almost identical leg pain can have very different causes, so the label alone is rarely enough to guide treatment:

The Sciatic Nerve and Its Path

The sciatic nerve forms from nerve roots that exit the lower spine, usually from the fourth lumbar level through to the third sacral level. Those roots join into one thick nerve that passes through the deep buttock, runs behind the hip and travels down the back of the thigh. Where it leaves the pelvis, the nerve is roughly as thick as an adult thumb. Just above the knee, it divides into branches that continue into the calf, the shin and the foot.

The Symptom Pattern That Sets Sciatica Apart

Ordinary low back pain tends to stay in the back, feels achy or stiff, and often eases with a change of position. That more familiar pattern of low back pain has different drivers and different management. Sciatic pain follows a line down the limb, feels sharp, burning or electric, and may come with numbness, tingling or a heavy weakness in the leg. Symptoms typically affect one side, and many people find the leg more troubling than their back.

The Clinical Term You May Hear

Health professionals use sciatica as shorthand for radiating leg pain of nerve origin. The clinical term is lumbar radicular pain, which points to a nerve root in the lower back as the source. Working out which root is involved, and what is irritating it, shapes your management plan.

Why Sciatic Pain Travels Down Your Leg

The leg is where you feel it, though it is rarely where the trouble starts. More than one mechanism can be involved at once:

Nerve Root Compression in the Lower Spine

Each nerve root leaves the spine through a small opening between two vertebrae. When something narrows that space, such as disc material bulging backwards or a thickened ligament, the root can be squeezed. The nerve does not report that squeeze as back pain. It reports a problem across the whole area it serves, which is why a millimetre or two of pressure near your waist can be felt in your foot.

Chemical Irritation Around the Nerve

Pressure is only part of the picture. When the outer wall of a disc tears, the inner material that leaks out is chemically irritating to nerve tissue. That inflammatory response can sensitise a nerve root even where imaging shows little physical compression. It helps explain why symptoms can be severe early and then settle as inflammation calms, well before any structural change.

Symptom Mapping Along a Dermatome

Every nerve root supplies a specific strip of skin, known as a dermatome, and a specific group of muscles, known as a myotome. Irritation at the fifth lumbar root often sends symptoms along the outside of the calf and into the top of the foot, while the first sacral root tends to affect the back of the calf and the sole or outer edge. Tracking where you feel symptoms helps a clinician work out which level is involved.

Nerve Irritation Beyond the Spine

Not all sciatic-type pain begins at the spine. The nerve passes through the deep buttock alongside the piriformis and other small muscles, and irritation there can produce similar symptoms without any nerve root being involved. This is sometimes called deep gluteal syndrome.

Common Causes of Sciatica

Sciatica is a consequence of something else happening in or near the spine, and the likely cause shifts with age, activity and general health:

Lumbar Disc Herniation

Disc herniation is the most frequent cause, particularly in adults aged about 30 to 50. A disc has a firm outer ring and a softer centre, and when that ring weakens, the inner material can push outwards and press on or inflame a nearby nerve root. Symptoms often start after bending, lifting or twisting, though many people cannot identify a trigger.

Spinal Canal Narrowing

Spinal stenosis describes a narrowing of the space where the spinal cord and nerve roots sit. It develops gradually alongside age-related changes to discs, joints and ligaments and becomes more common after 60. Leg symptoms typically build with standing and walking, then ease within minutes of sitting or leaning forward over a trolley or bench.

Vertebral Slippage

Spondylolisthesis occurs when a vertebra shifts forwards on the one below it, which can reduce the space available for a nerve root. It may follow a stress fracture in a younger athlete or develop through joint wear in later life. Back pain combined with leg pain is common, along with a sense of instability in certain positions.

Deep Gluteal and Piriformis Involvement

Long periods of sitting, a heavy fall onto the buttock or a rapid increase in running volume can irritate the nerve in that same region. Tenderness in that area and discomfort that worsens the longer you sit are common features, and they can overlap with gluteal tendon problems.

Pregnancy-Related Changes

Hormonal shifts, altered posture, changed weight distribution and increased load through the pelvis can all irritate the sciatic nerve during pregnancy. Symptoms are usually temporary, and gentle exercise, position changes and support strategies may help. Any nerve symptoms during pregnancy are worth raising with your treating team.

Less Common Causes

Infection, inflammatory conditions, fractures, cysts and tumours account for a very small share of cases. They are the reason clinicians ask about weight loss, night pain, fever, cancer history and recent illness during an assessment. These questions are routine and not a sign that anything serious has been found.

Symptoms That Point to Sciatica

Symptoms vary between people and can shift from week to week, though the pattern usually includes:

Radiating Pain Below the Knee

Pain that travels past the knee suggests nerve involvement more strongly than pain stopping in the buttock or thigh. Some people feel it constantly, while others notice it only in certain positions.

Altered Sensation in the Leg and Foot

Pins and needles, numbness or a patch of skin that feels dulled can accompany the pain and sometimes appear with very little of it. The location of these changes often gives a better clue to the nerve level involved than the pain itself.

Muscle Weakness on One Side

Some people notice difficulty pushing off the toes, lifting the front of the foot or rising from a low chair on the affected side. Mild weakness is common and often improves as the nerve settles.

Symptom Changes With Position and Activity

Coughing, sneezing, straining, sitting for long stretches and bending forward often intensify symptoms because each increases pressure around the nerve root. Walking may ease disc-related symptoms while worsening those linked to canal narrowing.

When to Seek Urgent Medical Care

Most sciatica is not dangerous. A few presentations need same-day assessment because they can indicate compression of the nerves at the base of the spinal cord. Contact a doctor immediately, or attend your nearest emergency department, if you notice any of the following:

• New difficulty controlling your bladder or bowels
• Numbness or altered sensation around the genitals, buttocks or inner thighs
• Leg weakness that is worsening quickly or affecting both legs
• Severe pain following a significant fall or accident
• Back pain with fever, unexplained weight loss or a history of cancer
• Severe pain that is worse at night and does not settle with rest

The list above is a general guide only. Anything that concerns you is worth having checked by a doctor, and Healthdirect Australia publishes a similar list of sciatica warning signs.

How Sciatica Is Diagnosed

Diagnosis relies mostly on your history and a hands-on examination, with scans further back in the process than many people expect. Assessment usually covers:

Detailed Symptom History

Your clinician will ask where symptoms travel, what brings them on, what settles them and how they have changed since they started. Questions about sleep, work, previous episodes and general health build the fuller picture. This part of the assessment often narrows the likely cause more than any test.

Physical and Neurological Examination

Movement testing shows which directions provoke or ease symptoms. Neurological testing checks reflexes, muscle strength and skin sensation to identify which nerve root may be involved. Nerve tension tests, such as raising the straight leg while lying down, help confirm whether the nerve is sensitised.

Selective Imaging Decisions

Australian guidance for low back pain discourages routine imaging when there are no warning signs, partly because disc bulges and age-related changes show up commonly on scans of people with no symptoms. Magnetic resonance imaging (MRI) or computed tomography (CT) scans become more useful when symptoms are severe, persistent or progressive, or when a specialist is weighing up an injection or surgery.

How Sciatica Is Usually Managed

First-line care focuses on settling the nerve, restoring confident movement and rebuilding capacity. Most plans combine:

Staying Active Within Comfortable Limits

Extended bed rest tends to slow recovery. Gentle, regular movement helps maintain circulation, joint mobility and confidence. Short walks, frequent position changes and continuing modified work where possible are usually encouraged, with intensity guided by how you feel the following day.

Restoring Movement Through Guided Exercise

A structured program may include directional preference exercises, nerve mobility work, hip and trunk strengthening and gradual loading. The mix depends on your presentation, and what suits a disc-related problem may not suit canal narrowing. Progression follows your response over days, not a fixed template.

Easing Symptoms With Hands-On Treatment

Manual therapy, soft tissue work and taping may offer short-term relief and make movement more comfortable. These approaches tend to complement active treatment, not replace it. Heat, ice and supported resting positions can also help you manage symptoms between appointments.

Managing Pain With Medical Input

Your general practitioner (GP) may discuss medicines suited to nerve pain and review them as symptoms change. Some people are offered a corticosteroid injection around the nerve root when pain is severe and limiting rehabilitation. Medicines and injections are generally used to make movement possible while the nerve recovers.

Adjusting Work and Daily Habits

Small changes often reduce daily irritation. Alternating sitting and standing, adjusting chair and desk height, breaking up long drives and reviewing how you lift and carry can all reduce load through the lower back. These adjustments are usually temporary while symptoms settle.

Building Strength for the Longer Term

Once symptoms ease, strength and conditioning work helps protect against recurrence. This typically involves progressive loading of the hips, trunk and legs, alongside general activity you enjoy and will keep doing. Many people finish rehabilitation feeling stronger than when they started.

What Recovery Typically Looks Like

Timelines vary widely, and the early weeks are often the most uncomfortable:

Timeframes for Improvement

Many cases of sciatica improve substantially within about six weeks to three months. Severe pain often eases earlier than numbness or tingling, which can linger while the nerve recovers. Some people still notice symptoms beyond a year, and ongoing management may be appropriate.

Signs of Genuine Progress

Improvement does not always show up as less pain first. Pain retreating up the leg towards the back, known as centralisation, is a positive sign even when the back itself feels sore. Longer comfortable periods, better sitting or walking tolerance and easier sleep are all meaningful markers.

Reasons for Slower Recovery

Very severe initial pain, significant nerve compression, high distress levels, poor sleep, smoking and long stretches of inactivity are all associated with slower recovery. Several of these can be influenced directly.

Steps for Preventing Recurrence

Varying your postures across the day, managing body weight and lifting with your legs all help. Consistency matters more than intensity. The broader habits behind keeping joints healthy after 50 apply here too, as spinal changes become more common with age.

When Sciatica Might Need Specialist Review

Most people never need to see a surgeon. Referral becomes worth considering in a few circumstances:

Symptoms That Are Not Settling

When leg pain remains disabling after a solid course of conservative care, commonly six to 12 weeks, a specialist opinion can clarify the options. Asking for that opinion does not commit you to surgery.

Nerve Changes That Are Worsening

Weakness that continues to worsen, or numbness that is spreading, warrants earlier review. These changes are assessed carefully because the pattern and speed of change influence how urgently further investigation is arranged.

Options That a Specialist May Discuss

Depending on the findings, a specialist may recommend image-guided injections, further imaging or surgical decompression of the affected nerve root. Surgery may shorten the time to pain relief for carefully selected people, while longer-term outcomes are often similar to non-surgical care. Any decision should weigh your symptoms, your goals and the risks involved.

Taking the Fear Out of Nerve Pain

Nerve pain is loud by design. The sciatic nerve covers so much ground that even modest irritation near your spine can make an entire leg feel unreliable, and that mismatch between how it feels and what is happening is what unsettles most people. Once you know the pain has an explanation, and that it is usually mechanical and time-limited, it becomes something you can work with.

You are not stuck waiting for it to pass, either. Movement, a considered plan and someone who can tell you what is safe to do this week are often enough to shift things forward. Many people get back to work and the activities they value, and the leg pain becomes an episode they managed, not a limit they live around.

If sciatica is keeping you from the things you enjoy, the team at MTP Health can assess what is driving your symptoms and build a plan around your goals. Speaking with your GP is also a sensible first step when symptoms are new, severe or changing.

Frequently Asked Questions (FAQs)

1. Is sciatica the same as a slipped disc?

No. A slipped disc is one possible source, while sciatica is the pattern of symptoms it can produce. Several other structures can irritate the same nerve, so the two terms are not interchangeable.

2. How long does sciatica usually last?

Many people improve considerably within six weeks to three months, though short flare-ups along the way are common. Symptoms lasting beyond that point are worth reviewing so the plan can be adjusted.

3. Should I rest or keep moving with sciatica?

Gentle, regular movement is generally preferred over extended rest. The right amount varies, and a clinician can help you find the level that eases symptoms without provoking a flare.

4. Do I need a scan to confirm sciatica?

Not usually. Diagnosis is generally made from your symptom history and a physical examination. An MRI or CT scan matters most when symptoms are severe, progressive or persistent, or when a specialist is weighing up an injection or surgery.

5. Can sciatica affect both legs at once?

Symptoms most often affect one side. Pain or numbness in both legs, particularly alongside bladder or bowel changes or numbness around the saddle area, needs urgent medical assessment.

6. What sort of exercise helps sciatica?

It depends on what is irritating the nerve. Some people respond well to extension-based movements, others to flexion-based positions, and hip and trunk strengthening usually plays a role once acute symptoms settle. A tailored assessment identifies which category you fall into and guides how quickly to progress.

7. Can sciatica come back after it settles?

It can, particularly where the original contributors have not changed. Recurrences are often milder and shorter when you already know what helped last time.

This article provides general information only. It does not take into account your personal circumstances, medical history or individual needs, and it is not a substitute for personalised advice. Speak with your GP, physiotherapist or another qualified health professional before acting on anything you read here, and seek immediate medical attention if your symptoms are severe or worsening.