Sciatica Explained: Why Your Leg Pain Starts in Your Back

Sciatica has a way of confusing people, because the pain is loudest in the wrong place. It burns, shoots or aches down the back of the leg, sometimes all the way to the foot, so that is where the attention goes, yet the problem is almost always sitting higher up, in the lower back.

That mismatch is the single most useful thing to understand about sciatica, because it explains why rubbing the leg does nothing and why the fix has to start at the spine. 

The reassuring headline, before any of the detail: most sciatica settles with time and sensible care, and only a small number of cases ever need anything dramatic.

Sciatica is a symptom, not a disease: the pain travels, but the problem sits in your spine

The word “sciatica” describes a pattern of pain rather than naming a single condition. The sciatic nerve is formed from several nerve roots that exit your lower spine, then joins up and runs through the buttock and down the back of the leg, with branches reaching the foot. 

When one of those nerve roots is irritated or compressed where it leaves the spine, the nerve carries that distress signal along its whole length, and your brain feels it in the leg, which is simply the far end of the wire.

So the leg pain is real, but it is referred: the source is a cranky nerve root in the back, not a problem in the leg itself. Treating where it hurts is exactly why so many people get nowhere; treating where it comes from is what works.

What sciatica feels like, and why it usually picks one leg

Sciatica has a recognisable signature. The pain radiates in a line from the buttock down towards the knee or foot, rather than sitting in a vague patch, and it often travels with pins and needles, numbness or a feeling of weakness in the leg.

It tends to flare when you cough, sneeze, bend or twist, all of which briefly raise the pressure on the nerve root. And because a given nerve root sits on one side of the spine, sciatica almost always affects just one leg. 

Where exactly you feel it, down the back of the calf, along the outside of the shin, or into particular toes, is a clue to which nerve root is involved, which is part of what a physiotherapist works out on examination.

True sciatica is this travelling, nerve-type pain; an ache confined to the buttock or hip without that radiating quality is often something else, so the pattern matters.

What is pressing on the nerve: usually a disc, sometimes a narrowing

Several things can irritate a lumbar nerve root, and they share a theme of reducing the space the nerve has to pass through. The most common by far is a herniated or bulging disc, where the soft cushion between two vertebrae pushes out and presses on the nearby root.

Other causes include a narrowing of the spinal canal that comes with age, a vertebra slipping slightly out of line, and, less often, more serious problems. 

Pregnancy can bring on sciatica too, as changing posture and ligament laxity load the lower back differently. The useful point for treatment is that most of these are mechanical and irritable rather than permanently damaged, which is why they tend to calm down as the inflammation around the nerve settles and the pressure eases.

The reassuring part: most sciatica improves without surgery

For all that it can be intensely painful, sciatica has a genuinely encouraging natural history. The majority of people improve over weeks to a few months, often with much of the gain in the first month or two, as the irritated nerve root settles. The old instinct to rest in bed actually slows this down; staying gently active, walking, and keeping up daily life as much as the pain allows is what current guidelines advise (NICE). 

A physiotherapist can speed and smooth that recovery by easing the most painful movements, using specific exercises to take pressure off the nerve, and rebuilding the strength and movement that protect your back afterwards.

Medication can help manage a bad flare, and for the small minority whose pain is severe or not settling, injections or surgery are options worth discussing, though they are the exception rather than the rule. 

For the day-to-day side of calming an episode, our tips for easing lower back pain are a practical starting point, and if you are weighing up your choices, our guide to the non-surgical options for back pain sets out what the evidence supports. The thread through all of it is the same: settle the nerve, keep moving, and rebuild.

When sciatica is an emergency: the signs that cannot wait

This is rare, but it is the one part of sciatica no one should gloss over. Occasionally the nerves at the very base of the spine are compressed severely enough to threaten the control of your bladder, bowel and the area between your legs, a condition called cauda equina syndrome. It is a genuine medical emergency, because delay can cause permanent damage.

Do not wait and see, and do not book a physiotherapy appointment for later; go to an emergency department straight away if sciatica comes with any of the following:

A few other features also warrant prompt, though not necessarily emergency, medical review rather than waiting it out: a history of cancer, unexplained weight loss, fever, severe pain that is worse at night, or a significant injury.

Ordinary sciatica does none of these; it is one-sided, mechanical, and eases when you find the right position. Knowing the difference is what lets you treat the common version calmly and act fast on the rare dangerous one.

Getting sciatica assessed at Befit Physio in Carlingford and North Kellyville

If leg pain has been shooting down from your back, an assessment pins down which nerve root is involved, rules out anything that needs a doctor, and gets you onto the movements and exercises that take pressure off it.

Settling a sciatic nerve and rebuilding the back behind it is part of our back and neck pain physiotherapy, and if the pain has been grumbling on for months rather than weeks, our approach to persistent back pain applies the same thinking over a longer horizon. 

You can be seen at our Carlingford physiotherapy clinic or with our North Kellyville physiotherapists.

Frequently Asked Questions

How long does sciatica last?

Most sciatica improves over a few weeks to a couple of months, with a lot of people feeling meaningfully better within the first month as the irritated nerve settles. A minority have symptoms that linger longer, sometimes up to a year, particularly if the problem is left unmanaged. Staying active and getting the right exercises early tends to shorten the course rather than drag it out.

Does sciatica go away on its own?

Often it does, because the usual cause is an irritated nerve root that calms down as the inflammation and pressure around it ease. That said, going away faster and more completely usually comes from staying gently active, avoiding bed rest, and doing targeted exercises rather than simply waiting. If it is not improving after a few weeks, or it keeps returning, it is worth getting assessed.

What is the fastest way to relieve sciatica?

There is no instant cure, but you can calm a flare by finding positions that ease the nerve, keeping gently mobile rather than lying still, using heat, and taking simple pain relief if appropriate. Beyond settling the flare, the lasting relief comes from specific exercises that reduce pressure on the nerve root and rebuild your back, which a physiotherapist can tailor to which nerve is involved.

What triggers sciatica?

Sciatica is usually triggered by something that compresses or irritates a nerve root in the lower spine, most commonly a bulging or herniated disc, and sometimes age-related narrowing of the spinal canal or a slipped vertebra. Pregnancy can bring it on too. Movements like bending, lifting and prolonged sitting can set off or worsen a flare, which is why posture and load matter in recovery.

When is sciatica a medical emergency?

Seek emergency care immediately if sciatica comes with loss of bladder or bowel control, numbness around the genitals or inner thighs, or numbness and weakness in both legs, as these can signal cauda equina syndrome, a rare but serious compression that needs urgent treatment. Prompt, non-emergency medical review is also wise if you have fever, unexplained weight loss, a cancer history, or severe night pain.

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