Lower back pain: causes, red flags and when to seek help

For most people the answer is a mechanical problem: a strained muscle, an irritated joint or a stiff set of ligaments in the lumbar spine. The NHS says it is not always obvious what causes back pain and that it often gets better by itself. A common trigger is an injury such as a pulled muscle, but many people cannot name a moment when it started.

Scans often show wear and tear that is as common in people without any pain as in those with it, which is why imaging is usually reserved for people with particular warning features rather than offered to everyone.

The NHS names slipped disc, sciatica (a trapped nerve) and ankylosing spondylitis as medical conditions that can lie behind back pain. Telling them apart comes down to where the pain travels, what it does at rest, and what makes it worse.

• The NHS describes sciatica as pain from the lower back down to the bottom and the back of one leg, often with pins and needles, numbness or weakness, and notes you probably do not have sciatica if you only have back pain.

• A slipped disc is described by the NHS as the most common cause of sciatica, followed by spinal stenosis, a slipped vertebra and back injury.

The NHS recommends seeing a GP if back pain has not improved after a few weeks of treating it at home, is stopping you doing daily activities, or leaves you worried or struggling to cope. It also lists the following as reasons to be seen.

• You have lost weight without trying.

• There is a lump or swelling in your back, or your back has changed shape.

• The pain does not improve with rest or is worse at night.

• The pain is worse when sneezing, coughing or pooing.

• The pain is high in the back, between the shoulders, rather than low down.

Cauda equina syndrome is a rare but serious squeeze on the bundle of nerves at the bottom of the spinal canal. The NHS says to call 999 or go to A&E if back pain comes with pain, tingling, weakness or numbness in both legs, loss of feeling around the genitals or anus, difficulty peeing or peeing or pooing yourself, changes in how the penis or vagina feels during sex, inability to get or keep an erection, or inability to orgasm. Chest pain and back pain that begins after a serious accident such as a car crash are also on the list.

The NHS sciatica page adds that sciatica on both sides, or severe or worsening weakness or numbness in both legs, are signs of a problem that needs treating in hospital as soon as possible.

The NHS advises asking for an urgent GP appointment or calling NHS 111 if you feel hot, cold, shivery or generally unwell with the pain, or if the pain is severe, starts suddenly or is quickly getting worse.

A clinician will ask when and how the pain began, whether it goes into a leg, whether it changes with posture, how it affects sleep, and whether you have had any bladder, bowel or sexual changes. They will check how you stand, bend and walk, test strength, reflexes and sensation in the legs, and may press along the spine.

Most people do not need a scan or blood test. When a scan is needed, an MRI of the lumbar spine is usually the most informative test for nerve compression, while blood tests may be used if inflammation or infection is suspected.

The NHS suggests staying active, carrying on with daily activities, and trying exercises and stretches for back pain. It says anti-inflammatory medicine such as ibuprofen may help but may not suit everyone, that paracetamol on its own is not recommended for back pain although it may be used with another painkiller, and that a pharmacist or GP can advise which painkiller is suitable for you.

An ice pack wrapped in a tea towel can reduce pain and swelling, while a heat pack or hot-water bottle wrapped in a towel can relieve stiffness and muscle spasm. Walking, swimming, yoga and pilates may also help, and the NHS says to stop and see a GP if exercises make the pain worse.

The NHS says that if pain is severe or not improving you may be prescribed painkillers, and that other options after a few weeks include group exercise and physiotherapy, manual therapy, cognitive behavioural therapy to help you cope with pain, and, for long-term lower back pain, a procedure to seal off nerves that carry pain signals. Surgery may be considered where a condition such as a slipped disc is responsible and other treatments have not helped.

Private physiotherapy, pain clinics and spinal surgeons offer faster access than some NHS routes, but the same principle applies: assessment first, imaging only when it will change management.