Lower back pain


  • May also be called lumbago, referring to pain in the muscles and joints of the lower back
  • Pain lasting > 6 weeks is risk factor for more serious disease
  • Night pain and unrelenting pain are worrisome symptoms
  • Back pain in IV drug user is spinal infection until proven otherwise
  • 95% of herniated discs occur at L4-L5 or L5-S1 (for both pain extends below the knee)

Back Pain Risk factors and probability of Fracture or Malignancy[1]

Factor Post Test Probability (95%CI)
Older Age (>65yo) 9% (3-25%)
Prolonged corticosteroid 33% (10-67%)
Severe trauma 11% (8-16%)
Presence of contusion or abrasion 62% (49-74%)
Multiple red flags 90% (34-99%)
History of malignancy 33% (22-46%)

Red Flag Symptoms of Low Back Pain [2]

Symptoms Corresponding Pathology
Age under 18 years Congenital abnormality
Age over 50 years Fracture, malignancy
Anticoagulant use Spinal hematoma
Fever Infection, malignancy
Genitourinary issues including urinary retention/incontinence or sexual dysfunction Cauda equina syndrome
Immunocompromised Fracture, infection
IV drug use Infection
Recent spinal surgery or epidural injection Infection, spinal hematoma
Trauma Fracture, spinal hematoma

Red Flag Signs of Low Back Pain[3]

Signs Corresponding Pathology
Reduced anal sphincter tone Cauda equina syndrome
Hyperreflexia Acute cord compression
Hyporeflexia/areflexia Cauda equina syndrome
Lower extremity muscle weakness Acute cord compression or Cauda equina syndrome
Saddle paresthesia/anesthesia Cauda equina syndrome
Absent or decreased bulbocavernosus reflex Cauda equina syndrome

Clinical Features

Symptoms by Causes of Low back pain

Musculoskeletal pain Spinal stenosis Sciatica Cauda equina syndrome Rheumatologic
Radiation? No Possible (can be bilateral) Yes (in the distribution of a lumbar or sacral nerve root) Possible ?
Worsened by: Movement (e.g. twisting of torso) Walking (pseudo-claudication) and prolonged standing Coughing, Valsalva, sitting Morning stiffness >30minutes
Improved by: Rest Forward flexion, especially sitting Lying in supine position Movement throughout the day
Other symptoms: Urinary/bowel disturbances, perineal anaesthesia Other rheum symptoms (e.g. ankylosing spondylitis, psoriatic arthropathy, IBD arthropathy, Reiter's disease)
Lumbar nerve root distribution

Waddell's Signs of Non-Organic Low back pain[4]

3 or more positives suggest non-organic or alternative organic source:

  • Over-reaction to the examination
  • Widespread superficial tenderness not corresponding to any anatomical distribution
  • Pain on axial loading of the skull or pain on rotation of the shoulders and pelvis together
  • Severely limited straight leg raising on formal testing in a patient who can sit forwards with the legs extended
  • Lower limb weakness or sensory loss not corresponding to a nerve root distribution

Differential Diagnosis

Differential diagnosis of back pain

Lower Back Pain



  • Straight leg raise testing
    • Screening exam for a herniated disk (Sn 68-80%)
    • Lifting leg causes radicular pain of affected leg radiating to BELOW the knee
    • Pain is worsened by ankle dorsiflexion
    • Pain may be relieved by pressing across biceps femoris and pes anserinus tendons behind knee ('bowstringing')
  • Crossed Straight leg raise testing (high Sp, low Sn)
    • Lifting the asymptomatic leg causes radicular pain down the affected leg
  • Nerve root compromise
  • Rectal exam, perineal sensation, palpable bladder?


  • Pregnancy test
  • Only necessary if concerned for infection, tumor, or rheumatologic cause
    • CBC, UA, ESR (90-98% Sn for infectious etiology)
  • Consider post void residual


  • Multiple institutions advise against routine initial imaging of the lumbar spine in adults with acute non-traumatic low back pain, in the absence of severe progressive neurologic deficit, absence of red flags, and if <6 weeks in duration.[5][6][7][8][9][10][11][12]
  • Plain films
    • May consider if suspect fracture, tumor, or infection, however, of low utility.
  • CT
    • Better for identification of fractures.
  • MRI
  • Ultrasound


Acute, Non-traumatic, Non-Radicular Back Pain

  • Instruct to continue daily activities using pain as limiting factor
  • Recommend at home stretches
  • Medications
    • Acetaminophen and/or NSAIDs
      • 1st line therapy
      • Consider gel/patch like diclofenac or ketoprofen (shown to be more effective than PO form and placebo in one study[13])
    • Lidocaine patch
    • Capsaicin or Cayenne
      • Skin desensitization upon repeated exposure
    • Muscle relaxants (limited evidence)
      • Cyclobenzaprine 10 mg PO OR
      • Methocarbamol 1500 mg PO
    • Opioids
      • Can be considered for moderate-severe pain but only for limited duration (<1 week)
      • Associated with higher return rates to ED within 30 days for same complaint when compared to other modalities

Not Indicated

Acute, Radicular Back Pain (Sciatica)

80% of patients will ultimately improve without surgery

Spinal stenosis

  • Treatment is the same as for musculoskeletal back pain

Cauda equina syndrome

  • Immediate spine surgery consultation for spinal decompression to avoid permanent bowel/bladder/neurologic injury
  • Most common in young men[17]
  • The onset of perineal anesthesia associated with bladder dysfunction is typical of the start of cauda equina syndrome and the time at which the clock starts on diagnosis and management.[18]
  • Painless urinary retention often has the greatest predictive value as a stand-alone symptom, but it is unfortunately indicative of late, often irreversible cauda equina syndrome[19]


  • Normally outpatient, as long as no signs of emergent pathology and able to ambulate

See Also

External Links


  1. Downie A, et al. Red flags to screen for malignancy and fracture in patients with low back pain: systematic review. BMJ. 2013; 347:f7095. [1]
  2. Depalma. Red flags of low back pain. JAAPA. 2020;33(8):8. doi:10.1097/01.JAA.0000684112.91641.4c
  3. Depalma. Red flags of low back pain. JAAPA. 2020;33(8):8. doi:10.1097/01.JAA.0000684112.91641.4c
  4. Waddell G, et al. Non-organic physical signs in low-back pain. Spine. 1980; 5:117-125.
  5. ACEP - Lumbar spine imaging in the ED | Choosing Wisely. October 27, 2014. Accessed March 30, 2023. https://www.choosingwisely.org/clinician-lists/acep-lumbar-spine-imaging-in-the-ed/
  6. American College of Physicians. Five Things Physicians and Patients Should Question. Choosing Wisely Campaign. February 24, 2015. Accessed March 10, 2023. https://www.choosingwisely.org/societies/american-college-of-physicians/
  7. American Academy of Family Physicians. Twenty Things Physicians and Patients Should Question. Choosing Wisely Campaign. 2021. Accessed March 10, 2023. https://www.choosingwisely.org/societies/american-academy-of-family-physicians/
  8. American Society of Anesthesiologists. Five Things Physicians and Patients Should Question. Choosing Wisely Campaign. Published 2019. Accessed March 10, 2023. https://www.choosingwisely.org/societies/american-society-of-anesthesiologists-pain-medicine/
  9. American College of Occupational and Environmental Medicine. Five Things Physicians and Patients Should Question. Choosing Wisely Campaign. Published 2022. Accessed March 10, 2023. https://www.choosingwisely.org/societies/american-college-of-occupational-and-environmental-medicine/
  10. American Association of Neurological Surgeons and Congress of Neurological Surgeons. Five Things Physicians and Patients Should Question. Choosing Wisely Campaign. Published June 24, 2014. Accessed March 10, 2023. https://www.choosingwisely.org/societies/american-association-of-neurological-surgeons-and-congress-of-neurological-surgeons/
  11. American Chiropractic Association. Five Things Physicians and Patients Should Question. Choosing Wisely Campaign. Published 2021. Accessed March 10, 2023. https://www.choosingwisely.org/societies/american-chiropractic-association/
  12. Five Things Physicians and Patients Should Question. Choosing Wisely Campaign. Published 2022. Accessed March 10, 2023. https://www.choosingwisely.org/societies/north-american-spine-society/
  13. Mazières B, Rouanet S, Velicy J, et al. Topical ketoprofen patch (100 mg) for the treatment of ankle sprain: a randomized, double-blind, placebo-controlled study. Am J Sports Med. 2005;33:515-523
  14. Holve, RL, et al. Oral steroids in initial treatment of acute sciatica. J Am Board Fam Med. 2008; 21(5):469-474.
  15. Goldberg H, et al. Oral steroids for acute radiculopathy due to a herniated lumbar disk: a randomized clinical trial. JAMA. 2015 May 19;313(19):1915-23. PMID 25988461.
  16. Friedman BW, et al. "Diazepam is no better than placebo when added to Naproxen for acute low back pain." Annals of EM. August 2017. 70(2):169-176
  17. Rider LS, Marra EM. Cauda Equina And Conus Medullaris Syndromes. In: StatPearls. StatPearls Publishing; 2023. Accessed March 29, 2023. http://www.ncbi.nlm.nih.gov/books/NBK537200/
  18. Quaile A. Cauda equina syndrome-the questions. Int Orthop. 2019;43(4):957-961. doi:10.1007/s00264-018-4208-0
  19. Todd NV. Guidelines for cauda equina syndrome. Red flags and white flags. Systematic review and implications for triage. Br J Neurosurg. 2017;31(3):336-339. doi:10.1080/02688697.2017.1297364