Sciatica: Symptoms, Causes of Sciatic Nerve Pain

The pain starts in the lower back, descends through the buttock and runs along the back of the leg — sometimes down to the foot and toes. This may be sciatica: irritation or compression of the sciatic nerve, the largest nerve in the body. Most often it resolves within a few weeks or months, but it can also return.

What sciatica and the sciatic nerve are

The sciatic nerve runs from the lower back to the feet and controls the muscles of the back of the knee and lower leg, and also provides sensation to the back of the thigh, part of the lower leg and the sole of the foot. Sciatica is not a disease in its own right but a symptom of a problem with this nerve: pain, weakness, numbness or tingling that begin in the lower back and descend down the leg, usually on only one side.

Symptoms of sciatica

The sensations in sciatica most often affect the buttock and the back of one leg, frequently including the foot and toes. A person may feel sharp burning pain along the back of the leg, tingling like pins and needles, numbness and weakness. Symptoms sometimes appear suddenly, but they can also increase gradually; the pain worsens with movement, sneezing or coughing. Back pain also occurs, but it is usually milder than the pain in the leg. If only the back is affected, it is most likely not sciatica.

Why the sciatic nerve hurts: main causes

Sciatica occurs when something presses on or rubs against the sciatic nerve. The most common cause is a herniated disc, when the soft cushion between the bones of the spine bulges outward; this more often happens with age. Other causes include narrowing of the part of the spine where the nerves pass (spinal stenosis), displacement of one of the vertebrae (spondylolisthesis) and back injury, such as a pelvic fracture. In some cases the cause cannot be found.

Buttock pain in sciatica

The buttock is a typical spot where the pain of sciatica is felt especially clearly, since this is where the nerve exits the pelvis and runs down the leg. The sensation may be sharp or burning, and it worsens with movement, coughing and sneezing. A similar picture is sometimes produced by piriformis syndrome, when the nerve is irritated in the buttock area, so the source of the pain is assessed by a doctor.

How sciatica is diagnosed and which doctor to see

To clarify the cause, the doctor may order a computed tomography or MRI scan of the spine. If the pain does not go away for several weeks, worsens or interferes with everyday activities, see a doctor; they will assess the cause of the pain and, if necessary, suggest further examination.

Warning signs: when a visit cannot be postponed

Some signs may indicate a serious back problem that needs to be treated in hospital as soon as possible. These include sciatica on both sides, marked or increasing weakness or numbness in both legs, numbness around the genitals or anus, difficulty starting urination, inability to hold urine or stool if this is unusual for you.

• pain radiates to the buttock and along the back of one leg
• tingling, numbness or weakness in the leg, sometimes down to the foot
• pain worsens with movement, coughing and sneezing
• back pain is milder than leg pain

On its own it is not a reason to call an ambulance; call 103 or 112 if sciatica has appeared on both sides, there is marked or increasing weakness or numbness in both legs, numbness around the genitals or anus, it is difficult to start urinating or urine or stool cannot be held if this is unusual for you.

This material is for reference: it helps you recognize your symptoms but does not replace a doctor's consultation — if in doubt, see a specialist.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer