Sciatica is nerve pain that travels from the lower back through the buttocks and down one leg. It can cause sharp or burning pain, tingling, numbness and muscle weakness, with symptoms sometimes worsening during prolonged sitting, movement, coughing or sneezing.
The condition occurs when the nerve roots that form the sciatic nerve become irritated or compressed. A herniated disc, commonly called a slipped disc, is one of the main causes, although other spinal conditions can also produce similar symptoms.
According to the UK National Health Service (NHS), sciatica often improves within a few weeks to several months, but some cases persist or recur.
What causes sciatica?
The sciatic nerve originates in the lower spine, passes through the buttocks and extends down each leg. Sciatica develops when the nerve or the nerve roots supplying it become irritated or compressed.
The condition usually affects one side of the body, although symptoms can occasionally affect both legs. Its severity varies, and not everyone experiences the same combination of symptoms.
Several conditions can cause sciatica.
1. Herniated or slipped disc
A herniated disc is one of the most common causes of sciatica. Spinal discs act as cushions between the bones of the spine, helping absorb pressure and allowing movement.
Each disc has a soft centre surrounded by a tougher outer layer. When part of the centre pushes through a weakened or torn outer layer, the protruding material can press on nearby nerve roots.
This pressure can trigger pain that travels from the lower back into the buttock and leg. Some people also experience numbness, tingling or weakness in the affected leg or foot.
Not every herniated disc causes symptoms. The effects depend partly on whether the disc presses on a nerve and the extent of that pressure.
2. Other spinal conditions
Sciatica can also develop when changes in the spine narrow the spaces through which nerves pass.
Spinal stenosis, a narrowing of the spinal canal, can place pressure on nerve structures. Bone spurs and spondylolisthesis, a condition in which one vertebra slips out of position relative to another, can also contribute to nerve compression.
Osteoporosis, a condition that weakens bones and increases the risk of fractures, is not considered a common direct cause of sciatica. However, a spinal fracture associated with osteoporosis can cause back pain and may require medical assessment.
3. Back injuries and nerve compression
An injury affecting the lower back can irritate or compress the nerve roots associated with sciatica. Symptoms may develop after an accident or another injury, although many cases occur without an identifiable triggering event.
Pain that spreads from the buttock down the back of the thigh and into the calf or foot can indicate nerve irritation. However, similar symptoms may arise from other conditions, so a medical assessment is necessary to establish the likely cause.
What are the symptoms of sciatica?
The main symptom is pain that follows the path of the sciatic nerve, usually from the lower back or buttock down one leg.
The pain can range from a mild ache to a sharp, burning sensation or an electric-shock-like feeling. Some people experience persistent discomfort, while others have pain that becomes more noticeable during particular movements.
Common symptoms include:
- Sharp or shooting pain extending down the buttock and leg.
- Burning sensations or tingling, sometimes described as pins and needles.
- Numbness in parts of the leg, foot or toes.
- Muscle weakness affecting the leg or foot.
- Pain that worsens after prolonged sitting or during coughing and sneezing.
Some people experience back pain alongside leg pain, but the leg symptoms may be more prominent.
Pain when standing up after sitting can occur in people with sciatica, although it is not a symptom experienced by everyone. The location and intensity of the pain also vary between individuals.
Sciatica should not be assumed whenever someone experiences back or leg pain. Other conditions can cause similar symptoms and may require different treatment.
What triggers sciatica?
Certain activities and positions can aggravate existing sciatic pain. Prolonged sitting is a recognised trigger, particularly when symptoms are associated with a herniated disc.
Bending, twisting, coughing and sneezing can also increase discomfort in some people. The effect of movement varies, and an activity that aggravates one person’s symptoms may not affect another in the same way.
Extended periods of bed rest or inactivity may delay recovery. The NHS recommends continuing normal activities as much as possible and introducing gentle movement rather than sitting or lying down for long periods.
Anyone experiencing recurring or worsening pain should seek medical advice to establish the cause rather than assuming that a particular activity is responsible.
How is sciatica diagnosed?
A healthcare professional will usually assess a patient’s symptoms, medical history and physical condition before determining whether the pain is consistent with sciatica.
The assessment may include questions about where the pain begins, how far it travels, when it started and whether the patient has experienced numbness or weakness.
A physical examination can help assess movement, muscle strength, sensation and nerve function.
Imaging is not routinely necessary in every case. An X-ray can show certain changes in the bones but cannot reliably confirm a herniated disc. Magnetic resonance imaging (MRI) can provide more detailed images of discs and other soft tissues when further investigation is clinically necessary.
The decision to request imaging depends on the symptoms, examination findings and whether the results are likely to affect treatment.
People should seek medical assessment if the pain is severe, becomes progressively worse or interferes with normal activities.
Some symptoms require emergency medical attention. These include new or worsening weakness or numbness in both legs, numbness around the genitals or buttocks, difficulty passing urine, or loss of bladder or bowel control. They may indicate serious compression of nerves in the lower spine.
How is sciatica treated?
Treatment depends on the underlying cause, the severity of symptoms and how long the condition has persisted. Many people improve without surgery.
Staying active and physiotherapy
Gentle movement and a gradual return to normal activities can help support recovery. Prolonged bed rest is generally discouraged because inactivity can make it harder to regain normal movement.
Physiotherapy may help patients improve mobility, build strength and learn exercises suited to their condition. A healthcare professional can recommend an appropriate programme based on the patient’s symptoms and physical assessment.
Activities that consistently worsen the pain may need to be modified while recovery progresses.
Pain relief
Medication may help some patients manage symptoms, but its suitability depends on individual circumstances. Anti-inflammatory medicines, for example, can cause side effects and are not appropriate for everyone.
A doctor or pharmacist can advise on suitable options, taking account of other medicines and existing health conditions. Patients should not assume that every painkiller is effective for nerve pain.
Surgery
Surgery is not necessary for most people with sciatica. It may be considered when a herniated disc or another spinal condition causes persistent, disabling symptoms despite appropriate treatment.
Surgery may also be necessary when severe nerve compression causes significant or progressive weakness or other serious neurological problems.
The decision depends on the cause of the symptoms, the findings of medical examinations and the expected benefits and risks of the procedure.
Sciatica can be painful, but many cases improve over time. Early assessment is important when symptoms are severe, persistent or accompanied by weakness, numbness or changes in bladder or bowel function.
