Sciatica: what it is, what it isn’t, and why getting the diagnosis right matters

“Sciatica” is one of those terms that gets used a lot — by patients, clinicians, and Google — but it’s also one of the most commonly misunderstood.

People are often told they have sciatica when what they actually have is back-related leg pain, nerve sensitivity, or sometimes something that isn’t nerve-related at all. That matters, because the treatment approach should change depending on what’s really going on.

What sciatica actually means

Strictly speaking, sciatica refers to pain caused by irritation or sensitivity of the sciatic nerve, most commonly originating from the lower back or pelvis.

People with true sciatic pain often describe:

• Pain radiating from the lower back or buttock into the leg

• Symptoms following a recognisable nerve pathway

• Pins and needles, numbness, or sometimes weakness

• Pain that is aggravated by certain movements or positions rather than a constant, dull ache

Although the sciatic nerve is often described as “running down the leg”, it doesn’t begin as a single structure. It is formed from several nerve roots in the lower spine, which join together in the pelvis to create the sciatic nerve. Lower down, around the knee, it then splits into other nerves that continue into the lower leg and foot.

Because this nerve pathway is continuous, irritation closer to the spine can still produce symptoms well below the knee, even though the original problem may be higher up.

Importantly, not all leg pain is sciatica, even when it travels down the leg — which is why accurate assessment matters.

Common causes of sciatic pain

Sciatic symptoms can arise from several different mechanisms, including:

• Disc-related irritation, often labelled as a “disc bulge” or “slipped disc”

• Reduced space around the nerve, due to joint changes or age-related degeneration

• Inflammatory nerve sensitivity, where symptoms occur without clear structural compression

• Less commonly, non-spinal causes that still irritate the nerve along its pathway

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In rare cases, sciatic-type symptoms can be related to more serious underlying conditions such as tumours, infections, or fragility fractures, or can follow significant trauma. These causes are uncommon, but are considered during assessment, particularly when symptoms don’t follow typical patterns or are accompanied by other concerning signs.

This is why a one-size-fits-all diagnosis doesn’t work. Two people with “sciatica” can have very different underlying drivers — and need very different management.

Why scans don’t always give the answer

Many people arrive having already had an MRI scan, often showing disc changes. The problem is that disc bulges and age-related changes are extremely common, even in people with no pain at all.

That means:

• A scan finding doesn’t automatically explain your symptoms

• Treating the scan rather than the person can lead to unnecessary fear or overly cautious advice

• Clinical assessment still matters — a lot

Understanding how your symptoms behave with movement, load, and position is often more useful than a picture taken while you’re lying still.

Do you always need rest?

In most cases, no.

While acute flare-ups may need short-term modification, prolonged rest is rarely helpful and can actually slow recovery. Most evidence-informed approaches now focus on:

• Maintaining movement where possible

• Gradual exposure to load

• Reducing fear around normal activity

• Improving confidence in movement again

This doesn’t mean “push through pain”, but it does mean guided, sensible activity rather than avoidance.

When sciatica needs urgent assessment

Although most sciatic pain is not dangerous, there are red flags that should be assessed urgently, including:

• Progressive or severe leg weakness

• Loss of bladder or bowel control

• Saddle numbness

• Pain following significant trauma

These are rare, but important to recognise. I would recommend reading the Cauda Equina Page for further information on this topic.

Why understanding your sciatica matters

This is where education plays a big role.

Both evidence and experience show that when people understand their problem, they engage better and make more meaningful progress. When you understand what’s driving your pain — and just as importantly, what isn’t — decisions about movement, exercise, work, and recovery become far clearer.

Good management isn’t about chasing pain away at all costs. It’s about restoring function, confidence, and control.

How physiotherapy can help

Effective physiotherapy for sciatic pain isn’t just about hands-on treatment. It involves:

• Careful assessment to identify the likely pain driver

• Clear explanation of what’s happening and why

• Individualised exercise and movement strategies

• Advice that fits real life, not textbook ideals

Sometimes hands-on treatment helps. Sometimes exercise is the priority. Often it’s a combination — but always with reasoning behind it.

Thinking about sciatic pain?

If you’re struggling with leg pain, nerve symptoms, or have been told you have sciatica but aren’t sure it fully fits, a proper assessment can help clarify what’s actually going on and what the most sensible next steps are.