Sciatica and slipped disc explained

What sciatica is

Sciatica is the name for pain caused by irritation or pressure on the sciatic nerve, the large nerve that runs from the lower back through the buttock and down the back of each leg. When this nerve is squeezed or inflamed, it can cause pain that travels from the lower back or buttock down the leg, sometimes as far as the foot. People often describe it as shooting, burning or like an electric shock, and it may come with tingling, numbness or weakness in the leg. Sciatica is a symptom rather than a diagnosis in itself — it tells you a nerve is being irritated, and the next question is what is causing that irritation.

The slipped disc

Between the bones of the spine sit discs that act as cushions, with a tougher outer ring and a softer centre. A slipped disc — more accurately a prolapsed or herniated disc — happens when the softer centre bulges out through a weak point in the outer ring. Despite the name, the disc does not actually slip out of place. If the bulge presses on a nearby nerve, it can cause sciatica. Discs can bulge with age as they lose water and become less flexible, and sometimes after lifting awkwardly, though often there is no clear trigger. Not everyone with a bulging disc has pain — many are found by chance on scans in people with no symptoms at all.

How it usually behaves

The natural course of sciatica is reassuring for most people. Although it can be very painful, it tends to improve over weeks to a few months as the inflammation settles and the disc bulge shrinks. Staying active is one of the most helpful things: gentle movement and continuing normal activities as much as pain allows tend to lead to better recovery than resting in bed, which can actually slow things down. Pain often eases gradually rather than all at once. Because most cases settle on their own, the initial focus is usually on managing pain, keeping moving and reassurance, rather than rushing into scans or procedures, which are reserved for specific situations.

Managing sciatica

Most sciatica is managed without surgery. Keeping as active as possible, using heat, and adjusting activities to avoid aggravating movements all help. Pain relief may be advised by a clinician or pharmacist, and physiotherapy provides exercises to ease pressure on the nerve and strengthen the back. In the UK, many areas offer self-referral to physiotherapy. If pain is severe, ongoing or not settling after several weeks, a GP may consider further options, including referral for assessment, imaging such as an MRI scan, or specialist treatments like injections. Surgery to relieve pressure on the nerve is considered only for a minority — for example, when there is significant, persistent weakness or pain that does not improve with other measures.

The red flags

A small number of symptoms turn back and leg pain into an emergency, because they can signal a rare but serious condition where the nerves at the base of the spine are squeezed (cauda equina syndrome). Warning signs include numbness or tingling around the genitals, buttocks or inner thighs (the area that would touch a saddle), loss of control of the bladder or bowels, difficulty passing urine, or new severe weakness or numbness in both legs. These need immediate emergency assessment. Sciatica with a fever, unexplained weight loss, or pain that is much worse at night or after a serious injury also needs prompt review. For ordinary sciatica without these signs, urgent care is not needed.