Sudden lower back pain is a very common symptom. I often hear stories from people who have been fine – no lower back pain at all, and then suddenly they get a really nasty pain that seems to come out of the blue. This suddenness can make you feel pretty anxious as it can be so unexpected it makes you wonder what on earth can be causing it and if there is something that you should be worried about.
This is especially true if you are experiencing severe back pain. In fact sudden lower back pain is not necessarily a sign that anything serious is wrong at all. There are a few different causes of lower back pain that can cause sudden unexpected pain.
Infection – Did you have a fever or illness of any kind before you got this sudden back pain? Are you feeling generally unwell? You can get localised spinal infections from a variety of illnesses.
Fractures – Did you fall over of have some kind of injury that might have caused you to have a bony injury to your back? Did this sudden back pain come on soon after the injury? Do you have a diagnosis of osteoporosis or do you suspect that you might have it? (Osteoporosis is a thinning of the bones that commonly happens in older post menopausal women and some men). This condition can cause spontaneous fractures sometimes.
Cancer - Have you got a history of cancer or have you recently lost weight unexpectedly? It is unusual to get sudden lower back pain with cancer but if you have these signs then you need to get checked out straight away.
Neurological - Does the pain extend down into one or both legs and do you have any tingling or numbness in your legs? Do you hae any changed sensation in your saddle area? Has it affected your bladder or bowel function? Do you feel as if your legs don’t belong to you, as if they are oddly out of control? If so go and talk to your doctor as you may have some nerve or spinal cord involvement.
Now these are the signs of a worrying problem – they are called red flags – and you can read more about them on this red flags page. However, bear in mind that a tiny percentage of people with back pain have these problems. Less than 1% in fact – so whilst it's important that you know what to look for and that you get checked out in fact it is very unlikely that any of these problems are the cause of your sudden lower back pain.
The most common cause of sudden lower back pain in my experience is a small facet joint strain which is often accompanied by muscle spasm. If you strain a small joint ion your back the muscles go into protective spasm to keep the area still and this can be really very painful. This is called non-specific or mechanical lower back pain.
The story of your back pain probably started some time ago without you even realising it. We subject our bodies to stresses and strains all the time and we are often not even aware we are doing it. Sustained poor postures, repetitive movements, insufficient breaks, poor fitness or smoking, all these mean that your back finds it harder and harder to deal with the stresses and strains of daily life.
The graph illustrates what happens. We can get away with throwing difficult daily activities at our backs for a really long time, but without realising it we are edging up towards that pain threshold. Then one day, something small and meaningless can tip us across into pain and we experience sudden lower back pain.
Please go and see your doctor to get checked out, even though its unlikely you need to make sure that you have no serious problems with your back.
1. NHS Clinical Knowledge Summaries - Non Specific or Simple Lower Back Pain Guidelines (2010).