Low back pain is a highly prevalent disease (up to 84% of adults have low back pain at some time in their lives).
There are many different versions of treatment guidelines from different countries.
Some review articles had summarized some common clinical red flag symptoms from these guidelines
Malignancy History of malignancy (e.g., cancer, neoplasm)
Unexpected weight loss
Fracture Significant trauma
prolonged use of corticosteroid
Infection Fever
HIV
Cauda equina syndrome (CES) Saddle anesthesia/perineal numbness
(Sudden onset) Bladder dysfunction (e.g. urinary retention, overflow incontinence)
Fecal incontinence
Progressive weakness in lower limbs/lower motor neuron weakness
Although some guidelines suggest "red flag" symptoms as an indication for earlier imaging exams, there are limited data to support the use of most of the red flags as an indication for early imaging.
However, when these symptoms occur, patients and healthcare professional should be aware of it.
Reference: https://pubmed.ncbi.nlm.nih.gov/29971708/
https://link.springer.com/article/10.1007/s00586-016-4684-0
