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5 Common Causes of Sciatica

June 11, 2025

Sciatica isn’t a diagnosis or disease – it’s a symptom. It means there’s pain along the sciatic nerve, which runs from your lower back down your leg. That pain usually comes from something pressing on or irritating the nerve along the way.

Sometimes it burns. Sometimes it tingles or goes numb. Either way, it’s hard to ignore.

So what causes it? We asked James Laiso, PT, a physical therapist with Hartford HealthCare Rehabilitation Network, to break down the most common reasons behind sciatic pain – and what to do next.

1. Herniated disc.

This is one of the most common causes of sciatica, often starting in the lower back.

“Think of the discs in your spine like firm shock absorbers between each vertebra,” says Laiso. “When one bulges or ruptures, it can press on a nerve, which can cause pain, numbness or tingling down the leg.”

A herniated disc can happen suddenly – like when lifting something heavy – but it’s usually the result of wear and tear over time.

Since discs have limited blood flow, movement and exercise help deliver the nutrients they need to stay healthy.

> Related: 3 Signs Your Back Pain Is Actually a Herniated Disk

2. Bone spurs.

As we age, the spine can develop bone spurs – extra bits of bone that form as the body tries to spread weight more evenly.

“These small growths often develop from arthritis or years of repetitive movement,” says Laiso. “Bone spurs don’t always cause symptoms, but when they do, sciatica is often the first sign.”

3. Spinal stenosis.

Spinal stenosis happens when the space in your spine gets tighter, which can crowd the nerves – including the ones that form the sciatic nerve.

“It’s often age-related, but not always,” says Laiso. “Things like thickened ligaments or bone spurs can shrink the space where nerves travel, which can make you uncomfortable, especially with certain movements.”

4. Piriformis syndrome.

There’s a small muscle deep in your buttock called the piriformis. It can press on the sciatic nerve and trigger pain if it tightens or spasms.

“This type of sciatica isn’t from the spine – it’s the muscle itself putting pressure on the nerve,” says Laiso. “It’s often linked to sitting too long, overuse or falling. Since it’s hard to prove directly, we usually diagnose it by ruling out other causes.”

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5. Injury or trauma.

Sometimes sciatica starts with an injury that impacts your lower back, pelvis or buttocks.

“If trauma causes swelling or shifts things around the sciatic nerve, you might feel pain, numbness or tingling,” says Laiso. “Nerves can be unforgiving – once they’re irritated, the pain can feel intense even if the actual damage isn’t.”

> Related: 5 Surprising Causes of Back Pain

Here’s when to talk to your doctor.

While it’s painful, you can usually manage sciatic symptoms on your own.

Try these simple steps:

• Walking or light stretching, as long as it doesn’t make your leg symptoms worse.
• Heat to relax tight muscles and ease discomfort.
• Over-the-counter pain meds to reduce both pain and inflammation.

But – don’t wait it out if home remedies aren’t helping.

“You don’t have to push through the pain,” says Laiso. “If your symptoms get in the way of your life, let’s work together on a plan to help you feel better.”