What Is Sciatica?

You have been sitting a while, and when you stand up, a sharp, burning line of pain runs from your lower back through your buttock and down the back of one leg — sometimes as far as the foot. Sitting made it worse, not better. That travelling pain has a name: sciatica. It is not really a disease in its own right. It is the pattern you feel when the sciatic nerve — the long nerve that leaves the lower spine, passes through the buttock, and runs down each leg — gets irritated or squeezed somewhere along its route. The short explainer above (about two and a half minutes) walks through the classic symptoms, and they will sound familiar to anyone who has had it: pain on one side only, usually in just one leg, often described as burning.

Step one: trace where the pain actually travels

The route is the clue. Ordinary back ache tends to stay around the back; sciatica leaves town. It follows the nerve's path downward, which is why it so often affects one leg rather than both, and why it can come with tingling, pins and needles, or a patch of numbness in the leg or foot. Think of it the way you would another irritated nerve — carpal tunnel syndrome in the wrist produces its symptoms in the hand for much the same reason: a nerve under pressure complains along the territory it serves. What is doing the pressing varies. A bulging or herniated disc in the lower spine is the usual suspect. A narrowed spinal canal, or a tight piriformis muscle deep in the buttock, can irritate the same nerve — the difference is untangled in "Piriformis Syndrome versus Sciatica", whose description puts it plainly: the piriformis muscle irritates the sciatic nerve and causes pain along the back of the leg and foot.

Step two: a hands-on examination before any scan

Most assessments start with conversation and movement, not machinery. A clinician will ask where the pain goes, what makes it flare — prolonged sitting is a classic aggravator — and whether there is any weakness or numbness. Then comes a physical examination: checking reflexes, leg strength, and sensation, and gently raising your straightened leg while you lie back to see whether that reproduces the travelling pain. That simple test stretches the nerve's route, so a positive result points back toward nerve irritation rather than a simple muscle strain. Scans are not the automatic first step; imaging is generally brought in when symptoms are not settling, when weakness is progressing, or when the examination raises a specific concern the clinician wants to look at directly.

Step three: settle the irritation, keep moving gently

Here's the part that surprises people: complete bed rest usually isn't the answer. Care typically starts conservatively — staying as active as pain comfortably allows, short walks, and physiotherapy-guided exercises and stretches. One stretch used for the piriformis, for example, rests one ankle against the opposite knee to ease the muscle that can press on the nerve. Heat or cold, posture changes at your desk, and breaking up long sits all help some people. Any medicine is a conversation for your own clinician, who knows your history; this article won't name doses, because the right choice depends on the person, not just the pain. If leg pain stays stubborn despite that first phase, a clinician may discuss further options — which, in a minority of cases where a disc is clearly pressing on the nerve and symptoms persist, can include a procedure. That decision comes after examination and imaging, never from the pain pattern alone.

Step four: know the few warning signs that change the pace

Most sciatica is miserable rather than dangerous, and many episodes ease gradually over a number of weeks. A few features, though, should move you from watchful waiting to urgent assessment the same day: new difficulty controlling your bladder or bowels, numbness around the saddle area where you would sit on a bicycle seat, or weakness in the leg that is getting worse — a foot that starts to drag, for instance. Those can signal heavy pressure on the bundle of nerves at the base of the spine, and that is an emergency-services or urgent-care conversation, not a routine appointment. If none of that applies but the pain simply won't quit, book the ordinary appointment anyway — you deserve a proper examination and a plan, not just patience.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician and researcher.

Frequently Asked Questions

Is sciatica a diagnosis?

Not quite — it names a symptom pattern rather than the underlying cause. It describes pain travelling along the sciatic nerve, usually down one leg. The diagnosis is whatever is irritating the nerve, such as a herniated disc, a narrowed spinal canal, or a tight piriformis muscle, which is why a proper assessment looks for the source.

Why does sciatica usually affect only one leg?

Because the irritation is usually localised to one nerve root or one side — one disc bulge, one tight muscle. As the anchor video's description notes, the pain is typically constant in only one side of the buttock or leg, and pain in both legs at once is rare. New symptoms affecting both legs, especially with bladder or bowel changes, should be assessed urgently.

Do I need an MRI scan straight away?

Not usually as a first step. Assessment generally starts with your history and a physical examination, including strength, reflexes, and the straight-leg raise. Imaging tends to follow when symptoms are not settling, weakness is progressing, or the clinician has a specific concern to investigate.

How long does sciatica take to settle?

It varies a lot. Many episodes ease gradually over a number of weeks with activity kept comfortable and physiotherapy-guided movement, while others linger and need a fuller plan. There is no honest single timeline — what matters is the trend: steadily improving is reassuring, while worsening weakness or the warning signs above mean you should be seen promptly.

Educational only — this article is general information about sciatica, not medical advice and not a diagnosis. New bladder or bowel difficulty, saddle numbness, or worsening leg weakness needs urgent assessment the same day.