What is sciatica?

What sciatica is

The sciatic nerve runs from the lower back to the feet. Sciatica is the name for symptoms that appear when something irritates or squeezes this nerve. The NHS describes it as pain caused by irritation or compression of the sciatic nerve.

Because several different problems can irritate the nerve, the underlying cause matters as much as the pain itself.

What it feels like

The NHS says sciatica symptoms usually affect the bottom and the back of one leg, often including the foot and toes. People describe a sharp or burning pain, tingling like pins and needles, numbness or weakness. Symptoms can start suddenly or slowly, and the pain may be worse when moving, sneezing or coughing.

Back pain may be present too, but the NHS notes it is usually not as bad as the leg pain, and that you probably do not have sciatica if you only have back pain. Ordinary low back pain has many other causes, described in What causes most low back pain?

Common causes

According to the NHS, a slipped disc is the most common cause of sciatica and becomes more likely with age. Other causes it lists are spinal stenosis (narrowing of the part of the spine where nerves pass through), spondylolisthesis (when one spinal bone slips out of position) and a back injury. Mayo Clinic adds that a herniated disc in the lower back can cause pain in the buttocks, thigh, calf and foot.

For a plain-language account of the disc problem behind many cases, see What is a slipped disc? The narrowing problem is covered in What is spinal stenosis? Both belong to the wider set Discs and nerves. The NHS also names smoking as something that can increase the chance of developing sciatica, and nicotine as something that weakens disc tissue.

How long it lasts

The NHS says sciatica usually gets better in a few weeks to a few months, but it can last longer and can come back if you have had it before. For managing symptoms, NHS guidance suggests carrying on with normal activities as much as possible, starting gentle exercise as soon as you can, and avoiding long periods of sitting or lying down. It adds that moving, even when it hurts, is not harmful and can help recovery. It also says paracetamol is unlikely to help, and that it is not clear how much anti-inflammatory painkillers such as ibuprofen help with sciatica. A pharmacist or clinician can advise on what suits an individual.

If pain is severe and these measures have not helped, the NHS says a person may be referred to a hospital specialist. Options it lists include an epidural or other painkilling injection, a procedure called radiofrequency denervation, and in some cases decompression surgery. Which of these is offered depends on the country and the clinician.

When to get help

The NHS advises seeing a GP if sciatica pain has not improved after trying home treatments for a few weeks, is getting worse, or is stopping you doing your normal activities.

It advises going to A&E or calling 999 (use your local emergency number elsewhere) if you have sciatica on both sides, severe or worsening weakness or numbness in both legs, numbness around or under the genitals or around the bottom, difficulty starting to pee or being unable to pee, or loss of control of your bladder or bowels when this is not normal for you. The NHS says these could be symptoms of a serious back problem that needs hospital treatment as soon as possible. The topic is also covered in When is back pain an emergency? Practice varies by country and by clinician.