What Is Sciatica and Why Does It Happen?

Sciatica is a type of nerve pain that occurs when the sciatic nerve or one of its nerve roots becomes irritated or compressed. Unlike general lower back pain, sciatica often travels from the lower back or buttock into the leg, sometimes reaching the calf or foot.

The pain can be mild or severe and may feel sharp, burning or like an electric shock. Tingling, numbness and weakness can also occur. While many cases improve with appropriate care, persistent or severe symptoms may require medical evaluation.

The sciatic nerve is the largest in the body. It is formed by nerve roots emerging from the lower spine and travels through the buttocks and down the back of each leg.

Sciatica develops when these nerve roots become compressed, irritated or inflamed. It usually affects one side of the body and can cause symptoms along the path of the nerve rather than only at the site of the underlying spinal problem.

The most characteristic symptom is pain that radiates from the lower back or buttock into the leg. The exact symptoms depend on which nerve root is affected and the degree of irritation.

• Sharp, shooting or burning pain

• Pain extending into the thigh, calf or foot

• Tingling or pins-and-needles sensations

• Numbness in the leg or foot

• Weakness in the affected leg

• Pain that worsens after prolonged sitting

• Increased pain with coughing, sneezing or certain movements

Some people experience significant leg pain with little lower back pain.

Sciatica is usually caused by pressure on a nerve root in the lower spine. A herniated disc is one of the most common causes. When the inner material of a spinal disc pushes through its outer layer, it can irritate a nearby nerve.

• Spinal stenosis: Narrowing of the spinal canal can compress nerves.

• Bone spurs: Osteoarthritis-related changes can create extra bone that puts pressure on nerves.

• Spondylolisthesis: One vertebra slips forward relative to another, potentially narrowing the space around a nerve.

• Spinal injuries: Trauma can affect structures surrounding the nerve.

Age-related changes, excess body weight, prolonged sitting and physically demanding activities can also increase the likelihood of developing sciatica.

Sciatica can occur at any age, but the risk tends to increase with age as spinal discs and joints undergo degenerative changes.

Other factors that may contribute include being overweight, having a physically demanding job, frequently lifting heavy objects, prolonged sitting and low levels of physical activity.

Poor physical conditioning can also reduce the strength and mobility needed to support normal spinal movement.

Diagnosis generally begins with the symptoms, medical history and a physical examination. A healthcare professional may assess muscle strength, reflexes, sensation and range of movement while looking at how pain travels through the leg.

Imaging is not routinely required when symptoms are mild and improving. An MRI may be considered when symptoms are severe, persistent or accompanied by neurological changes. In selected cases, nerve conduction studies or electromyography may help assess nerve function.

Treatment depends on the underlying cause and severity of symptoms. Many people improve with non-surgical management.

Although severe pain may temporarily limit movement, prolonged bed rest is generally discouraged. Gentle activity can help maintain mobility and prevent deconditioning. A gradual return to normal activities is usually preferable to remaining inactive for extended periods.

Physiotherapy can help improve mobility, strength and movement patterns. A personalised programme may include:

• Lower-back and hip mobility exercises

• Core, hip and leg strengthening

• Flexibility exercises

• Movement and posture training

• Gradual return to everyday or athletic activities

Exercises should be adapted to the individual, particularly when nerve symptoms are present.

Pain-relieving medicines may be considered when symptoms interfere with daily activities, although their suitability varies between individuals. For persistent or severe symptoms, clinicians may consider other interventions, including targeted injections.

Because sciatica may involve neuropathic pain, cannabinoid-based medicines are also prescribed as a potential option within broader pain management. However, these medicines should be considered under medical supervision.

Surgery is generally reserved for selected cases, particularly when there is significant or progressive nerve weakness or persistent symptoms despite appropriate non-surgical treatment.

Most cases of sciatica are not emergencies. However, certain symptoms can indicate serious nerve compression and require urgent assessment.

Seek medical attention promptly if experiencing:

• New or worsening weakness in the leg

• Numbness around the groin, inner thighs or buttocks

• Loss of bladder or bowel control

• Severe symptoms following a significant injury

• Rapidly worsening neurological symptoms

These symptoms should not be managed at home without medical evaluation.

Not every case can be prevented, particularly when structural problems in the spine are involved. However, maintaining regular physical activity and good muscle strength can support spinal health.

Avoiding prolonged sitting, maintaining a healthy weight, strengthening the core and lower body and using safe lifting techniques may help reduce strain on the lower back.

The focus of long-term management should be more than temporary pain relief. Restoring mobility, strength and everyday function while addressing the underlying cause can help support recovery and reduce the impact of future episodes.