Red flags of low back pain (mnemonic)

Last revised by Craig Hacking on 18 Aug 2021

Low back pain is a very common condition among primary care patients. Most patients have nonspecific low back pain (85-90%) and would have unremarkable radiographs. The purpose of the red flags is to aid in the recommendation for imaging of the spine. A mnemonic to remember the red flags of low back pain is:



  • T: trauma
  • H: history of cancer
  • E: extended duration (>4-6 weeks)
  • R: rest or night pain
  • E: equina
  • D: disability
  • F: fever
  • L: losing weight
  • A: age <20 or >50
  • G: general symptoms
  • S: steroid use or immunosuppression

Equina refers to cauda equina syndrome (CES). Signs and symptoms of CES include: saddle anesthesia, bladder and sphincter dysfunction, progressive motor and sensory deficit in lower limbs, sciatica, and gait disturbance.

Disability refers to neurological dysfunctions not necessarily related to CES such as motor weakness and/or paresis in the lower limbs.

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