Red flags in low back pain

I noticed I have someone booked into an upcoming session to see me about back pain, so I decided it was time I checked the list of red flags for back pain to be sure I don’t miss anything. This worthy endeavour proved slightly more complicated than I’d expected.

I started off with the BMJ Learning module, but this seemed to be entirely geared towards helping people manage their back pain in the long term. Very important and I will finish the module… but it didn’t answer my question. (On the plus side, at least I’ll have something to write on the ‘reflection’ bit.) I looked up the NICE guidance itself, but, to my surprise, they also didn’t include a ‘red flags’ list, which seems like quite an omission.

So I searched for an article I remembered reading in the BMJ some years back, which turned out to be this one. However, as I read it, I realised that their definition of ‘red flag’ seemed to be ‘anything that makes things more complicated than the standard give-out-reassuring-advice scenario’, which is helpful in its own way but less so when what you’re looking for is ‘things it would be really bad to miss’.

I therefore did a bit more digging, and discovered that the actual problem is that nobody can quite agree on what the red flag list should be, and there seems to be less evidence than would be ideal. On the plus side, this meant I wasn’t missing anything obvious. Also on the plus side and more practically so, this article did list the four big causes of back pain I don’t want to miss:

  • Malignancy
  • Fracture
  • Infection
  • Cauda equina

And I’m also going to add a subcategory of the first as a separate category:

So, that was a useful starting point for my thinking. I also then managed to find another and probably better list in this, older, BMJ article. So, putting it all together, here’s the list of signs I need to take seriously:

Malignancy (including SCC) or cauda equina:

  • History of cancer
  • Unintentional weight loss
  • Severe unremitting pain
  • Progressive pain
  • Pain disturbing sleep
  • Pain worse on coughing/straining (because of epidural plexus distension in SCC)
  • Severe progressive neurological deficit in legs
  • Gait disturbance
  • Rapid decline in ability to walk/stand
  • Saddle anaesthesia (this includes buttocks/posterosuperior thighs as well as perineum, and can be unilateral and/or consist of altered sensation rather than sensory loss)
  • Urinary retention/constipation
  • Incontinence/overflow
  • Loss of anal sphincter tone


  • Trauma
  • History of prolonged or recent steroid use


  • High fever
  • Feeling unwell
  • Use of immunosuppressants


There are a few more things that typically show up on red flag lists, but I’m not sure how significant they are:

  • Thoracic pain
  • Age <20 yrs
  • Age >55 yrs

Finally, some things that aren’t red flags still need to be remembered. Firstly, signs of inflammatory back pain. Secondly, yellow flag signs; these are psychosocial signs indicating patients at high risk of developing chronic pain and disability. The latter are as follows:

  • A negative attitude that back pain is harmful/likely to be significantly disabling
  • An expectation that passive, rather than active, treatment will be helpful
  • Fear avoidance behaviour/reduced activity levels
  • A tendency to depression/low morale/social withdrawal
  • Social or financial problems




About Dr Sarah

I'm a GP with a husband and two young children.
This entry was posted in Back pain, Credits 2019, Don't miss, Musculoskeletal. Bookmark the permalink.

1 Response to Red flags in low back pain

  1. Pingback: Back pain – NICE guidelines | A Spoonful Of Sugar

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