Patient: “Doctor, I’ve had this pain running from my back down my leg for weeks now. Sometimes it’s sharp, other times it feels like numbness. I thought it was just back pain, but it’s not going away. What could be causing it?”
Doctor: “It sounds like sciatica. This happens when the sciatic nerve gets compressed or irritated. The nerve runs from your lower spine through your hips and legs, so when something presses on it, the pain can travel down that path. The causes can vary, from a slipped disc to age-related changes in your spine.”
This short dialogue shows what many people with sciatica experience. Sciatica isn’t just “ordinary back pain.” It develops because something is interfering with the sciatic nerve. Understanding the causes behind it is the first step in finding the right treatment and preventing symptoms from getting worse.
The Main Reasons Sciatica Develops
Several medical conditions directly affect the spine and are the most common culprits behind sciatica. These primary causes often lead to irritation, pressure, or inflammation of the sciatic nerve.
Herniated or Slipped Disc
This is the leading cause of sciatica. Between each spinal bone (vertebra) are soft discs that act like cushions. If one of these discs bulges out or ruptures, it can press against the sciatic nerve. The result is sharp, radiating pain that travels down the leg.
Spinal Stenosis
Spinal stenosis means the space within the spinal canal has narrowed. This narrowing squeezes the nerves, including the sciatic nerve roots. Patients often notice that their pain worsens when standing or walking for long periods, but eases when sitting or bending forward.
Degenerative Disc Disease
As people age, the discs in the spine lose flexibility and cushioning. When discs shrink or break down, the vertebrae may rub against each other, creating pain and sometimes irritating the nearby nerve roots. This age-related wear and tear can easily lead to sciatica.
Bone Spurs
Bone spurs are extra bony growths that form on the spine, usually as a result of arthritis. These small growths can press on the nerves around the spinal cord and trigger sciatica symptoms.
Spondylolisthesis
This condition occurs when one vertebra slips forward over another. Even a small shift in the spine’s alignment can pinch the sciatic nerve and cause pain. This type of sciatica often becomes worse with physical activity.
Other Conditions That Can Trigger Sciatica
Not all sciatica cases come from spinal problems alone. In some situations, other health conditions or physical changes can also irritate the sciatic nerve.
Muscle Spasms (Piriformis Syndrome)
The piriformis muscle, located deep in the buttock, lies close to the sciatic nerve. If this muscle tightens or spasms, it can press directly on the nerve. Though less common than spinal causes, it produces similar leg pain and numbness.
Pregnancy-Related Pressure
During pregnancy, the growing uterus and changes in posture can put additional strain on the lower back and sciatic nerve. Many expectant mothers experience temporary sciatica, especially in the later months.
Trauma or Injury to the Spine
Accidents, falls, or sports injuries can damage spinal structures or directly affect the nerve roots. Even if the injury heals, scar tissue or misalignment may continue to irritate the sciatic nerve.
Tumors (Rare but Possible)
In very rare cases, tumors in or near the spine may press on the sciatic nerve. While uncommon, this possibility shows why it’s important to seek medical advice for persistent or unexplained pain.
Lifestyle Choices and Risk Factors That Increase the Chances
Even if a person doesn’t have a specific spinal condition, certain habits and risk factors make sciatica more likely to develop or worsen.
Sedentary Lifestyle and Poor Posture
Sitting for long hours without movement, especially with poor posture, puts continuous strain on the lower spine. Over time, this pressure increases the risk of nerve irritation.
Obesity and Excess Weight
Carrying extra weight adds stress to the spine, particularly the lower back. This extra pressure can lead to disc problems or worsen existing spinal conditions that cause sciatica.
Prolonged Sitting or Heavy Lifting at Work
Jobs that involve either sitting all day (such as desk work or driving) or frequent heavy lifting increase the risk. Repetitive stress on the lower spine makes sciatica more likely to appear.
Age-Related Changes
As people get older, natural wear and tear of the spine becomes unavoidable. Conditions like degenerative disc disease, arthritis, and spinal stenosis are more common with age, all of which are major causes of sciatica.
Why Age Plays a Role in Sciatica Causes
Sciatica can affect people of all ages, but the underlying reasons often differ between younger and older adults. Understanding these differences helps explain why a 25-yearold with sciatica might face very different challenges than someone in their 60s.
Younger Adults
In younger people, sciatica is more commonly linked to sudden or mechanical issues with the spine. Since their spinal structures are still strong and flexible, problems usually occur because of acute injury, strain, or disc changes rather than natural wear and tear.
- Herniated or slipped discs are one of the leading causes in people under 40. A disc can bulge or rupture due to heavy lifting, intense sports, or even a sudden awkward movement.
- Trauma or accidents, such as falls or sports injuries, are also more likely triggers in this age group.
- Lifestyle habits, like prolonged sitting with poor posture or working jobs that involve repetitive bending or lifting, can also contribute to early sciatica.
In short, younger patients often develop sciatica due to specific events or injuries that directly irritate the nerve.
Older Adults
In older individuals, the story changes. The spine naturally undergoes wear and tear over time, and these changes are often the driving forces behind sciatica in this age group.
- Degenerative disc disease becomes more common as discs lose flexibility and cushioning.
- Spinal stenosis, or narrowing of the spinal canal, is particularly frequent in older adults and is a leading cause of persistent sciatica.
- Bone spurs and arthritis can also appear with age, placing pressure on the sciatic nerve.
- Spondylolisthesis, where one vertebra slips forward over another, is also more common with aging.
For older adults, sciatica often develops gradually, starting as mild stiffness or occasional pain, and progressing over time as spinal structures deteriorate.
This contrast shows how age shapes the cause of sciatica—younger people tend to experience sudden, injury-based causes, while older adults face progressive, degenerative ones.
Crux of the Matter
No matter the age group, one fact remains the same; sciatica is not a condition to ignore. The pain and discomfort are only symptoms of a deeper issue. That’s why identifying the root cause, whether it’s a slipped disc, age-related spinal changes, or even muscle-related pressure, is the most important step toward lasting relief.
By understanding what is actually pressing on or irritating the sciatic nerve, doctors can choose the right treatment, ranging from conservative care like physical therapy to more advanced options if needed. Without this step, treatment may only mask symptoms rather than solve the underlying problem.
The takeaway is simple! Don’t just treat the pain; find out why it’s happening. A clear diagnosis leads to targeted treatment, faster recovery, and a better chance of preventing future flare-ups.