Nonspecific musculoskeletal low back pain accounts for 80–90% of all acute low back pain presentations. [1-2] It is defined as pain below the costal margin and above the inferior gluteal folds without an identifiable specific pathoanatomical cause. Most patients improve substantially within the first month regardless of treatment. [2-3]
The following clinical algorithm from the AAFP provides a useful framework for evaluation and management:
1. History
- Use the OLD CARTS mnemonic: onset, location, duration, character, alleviating/aggravating factors, radiation, temporal factors, severity [1]
- Characterize pain: axial vs. radiating, constant vs. intermittent, mechanical (worse with activity, better with rest) vs. inflammatory (morning stiffness, improves with exercise)
- Ask about precipitating event (lifting, twisting, trauma, new activity)
- Occupation: prolonged sitting, recurrent heavy lifting, physical labor [1]
- Smoking status — associated with both acute and chronic LBP; cessation improves pain scores [1]
- Screen for mood disorders: anxiety, depression, catastrophizing — all increase risk of acute LBP and chronification [1][4]
- Important negatives: no bowel/bladder dysfunction, no saddle anesthesia, no progressive weakness, no fever, no weight loss, no history of cancer or IV drug use
2. Alarm Features
Red flag findings require immediate evaluation: [1][5]
- Cauda equina syndrome: new urinary retention, fecal incontinence, saddle anesthesia, bilateral leg weakness, decreased rectal tone
- Spinal infection (epidural abscess/osteomyelitis): fever, IV drug use, immunosuppression, indwelling catheters, recent bacteremia (LR+ 14–16 for epidural abscess with IVDU/catheter) [6]
- Malignancy: history of cancer + new LBP (LR+ 28), unexplained weight loss, pain at night, failure to improve after 1 month, age >50 with multiple risk factors [1][6]
- Vertebral fracture: significant trauma, or minor trauma + age ≥75, osteoporosis, chronic corticosteroid use (LR+ 31 with trauma + neurologic deficit); multiple red flags raise fracture probability to 42–90% [6]
- Abdominal aortic aneurysm: abdominal discomfort, pulsatile mass, male >50 who smokes [1]
- Aortic dissection: sudden tearing/ripping pain radiating to back, blood pressure differential between arms, new aortic regurgitation murmur [7]
3. Medications
First-line pharmacotherapy
- NSAIDs (e.g., ibuprofen 400–600 mg q6–8h, naproxen 250–500 mg q12h): low-to-moderate pain reduction and functional improvement; first-line across multiple guidelines [1][3]
- Nonbenzodiazepine muscle relaxants (cyclobenzaprine 5–10 mg TID, methocarbamol 750–1500 mg QID, tizanidine 2–4 mg TID): moderate-certainty evidence for small pain improvement; increased sedation risk; not strongly recommended by guidelines [1]
For radicular pain
Avoid
- Acetaminophen — no better than placebo for LBP [1-2]
- Gabapentin/pregabalin — no better than placebo; significant adverse effects and misuse potential [1]
- Opioids — do not significantly reduce acute LBP except in acute traumatic injuries; not recommended [1]
- Benzodiazepines — low efficacy, high harm potential; recommended against [1]
Cautions
- NSAIDs: GI and renal risks, especially in older adults and those with CKD [2]
- Muscle relaxants: sedation, dizziness; avoid in elderly or those operating machinery
4. Diet
- Weight management is critical: obesity is a significant risk factor for both acute and chronic LBP; weight loss (including from bariatric surgery) results in pain reduction [1]
- No specific dietary triggers for musculoskeletal LBP
- Adequate hydration and anti-inflammatory dietary patterns (fruits, vegetables, omega-3 fatty acids) may be supportive but lack strong LBP-specific evidence
- Walking ~100 minutes/day has been associated with reduced chronic LBP risk in a dose-response fashion [8]
5. Review of Systems
- Neurologic: weakness, numbness, tingling, gait changes, bowel/bladder dysfunction
- Constitutional: fever, chills, night sweats, unexplained weight loss (infection, malignancy)
- GI: abdominal pain, nausea, vomiting (referred pain from pancreatitis, cholecystitis, peptic ulcer)
- GU: urinary symptoms, flank pain (nephrolithiasis, pyelonephritis, prostatitis)
- Vascular: claudication symptoms (vascular vs. neurogenic), pulsatile abdominal mass
- Rheumatologic: morning stiffness >30 min, improvement with exercise, joint swelling (inflammatory spondyloarthropathy)
- Psychiatric: depression, anxiety, sleep disturbance, catastrophizing [1]
6. Collateral History and Family History
- Collateral from family/coworkers regarding functional limitations, medication use, substance use
- Family history of ankylosing spondylitis or HLA-B27-associated conditions
- Family history of osteoporosis (fracture risk)
- Family history of cancer (especially spine metastases)
- Social context: workers' compensation claims, secondary gain, job satisfaction — all influence chronification risk [4]
- Heritability contributes 21–67% of back pain burden in twin studies [4]
7. Risk Factors
- Sedentary lifestyle and prolonged sitting [1]
- Occupational: heavy lifting, repetitive bending/twisting, vibration exposure, poor job satisfaction [4]
- Obesity [1][9]
- Smoking [1][9]
- Depression, anxiety, catastrophizing [1][4]
- Prior episodes of LBP [10]
- Female sex [4]
- Age: prevalence higher in those >40 years [2]
- Poor coping mechanisms and fear-avoidance behavior [4]
8. Differential Diagnosis
Cannot-miss diagnoses
- Cauda equina syndrome (prevalence ~0.04% of LBP presentations) [6]
- Epidural abscess / vertebral osteomyelitis (0.01%) [6]
- Malignancy (0.7%) [6]
- Vertebral compression fracture (~4%) [11]
- Abdominal aortic aneurysm (referred pain) [1]
- Aortic dissection [7]
Common specific spinal causes (10–20% of LBP)
- Herniated nucleus pulposus (leg > back pain, positive SLR)
- Lumbar spinal stenosis (neurogenic claudication, relief with flexion)
- Spondylolysis/spondylolisthesis (extension-based pain, adolescents/athletes)
Referred pain mimics
- Nephrolithiasis, pyelonephritis
- Pancreatitis, peptic ulcer disease, cholecystitis
- Endometriosis, PID, prostatitis
- Herpes zoster (prodromal pain before rash) [1]
Inflammatory
9. Past Medical History
- Previous episodes of LBP and their duration/treatment
- History of osteoporosis or fragility fractures
- Cancer history (especially breast, lung, prostate, renal, thyroid — common spine metastases)
- Immunosuppression (HIV, transplant, chronic steroids)
- IV drug use history
- Prior spinal surgery or injections
- Chronic conditions: diabetes, CKD (affects NSAID use), depression/anxiety
- Chronic corticosteroid use (fracture risk)
10. Physical Exam
Observation
- Gait: antalgic gait, wide-based gait (stenosis), flexed posture/"shopping cart sign" (spinal stenosis) [1]
- Spinal alignment, scoliosis, kyphosis
Palpation
- Midline spinous process tenderness — concerning for fracture, infection, malignancy [1]
- Paraspinal muscle tenderness — typical of musculoskeletal strain; achy, intermittent, unilateral, rarely radiating [1]
- Sacroiliac joint tenderness
Range of motion
- Flexion, extension, lateral bending, rotation
- Pain with flexion → discogenic; pain with extension → posterior elements (facet, spondylolysis) [12]
Neurologic exam (focused on L4, L5, S1)
- Motor: hip flexion (L2-L3), knee extension (L4), ankle dorsiflexion/great toe extension (L5), ankle plantarflexion (S1) [12]
- Heel walk (L5) and toe walk (S1) [13]
- Reflexes: patellar (L4), Achilles (S1)
- Sensation: medial foot (L4), dorsal foot (L5), lateral foot (S1)
- Rectal tone if cauda equina suspected
Special tests
- Ipsilateral straight-leg raise (SLR): 92% sensitive for L5-S1 disk herniation [2][14]
- Crossed SLR: 90% specific for disk herniation [2][14]
- Abdominal palpation: pulsatile mass (AAA) [1]
11. Lab Studies
Not routinely indicated for nonspecific musculoskeletal LBP [1][15]
Order when red flags present
- CBC: infection, malignancy
- ESR, CRP: infection (osteomyelitis/abscess), malignancy, inflammatory spondyloarthropathy [1]
- HLA-B27: if inflammatory spondyloarthropathy suspected [1]
- Urinalysis: if renal etiology suspected
- D-dimer: if aortic dissection is in the differential (high negative predictive value) [16]
- Troponin: if chest/back pain raises concern for ACS vs. dissection [16]
12. Imaging
Most patients with acute LBP do not require imaging [1-2]
When to image
- Trauma (especially with osteoporosis risk): AP/lateral lumbosacral radiographs first [1]
- Suspected cauda equina, infection, malignancy: MRI is preferred (CT if MRI contraindicated) [1]
- Suspected AAA: abdominal ultrasound or CT [1]
- Suspected aortic dissection: CTA of the aorta [17]
- Pain persisting >8 weeks despite appropriate therapy: consider MRI to identify specific causes [1]
Key points
- Plain radiographs are not useful for herniated disk or spinal stenosis [1]
- Imaging abnormalities are common in asymptomatic individuals (most people have disc degeneration by age 40) and correlate poorly with symptoms [4]
- Early imaging in uncomplicated LBP does not improve outcomes [2][18]
13. Special Tests
- STarT Back Screening Tool: 9-item validated questionnaire to stratify risk of chronification (medium-to-high score = higher risk) [1]
- Oswestry Disability Index (ODI): self-assessed disability; moderate or higher scores predict chronic LBP [1]
- Bladder scan/post-void residual: if cauda equina suspected (PVR >200 mL is concerning) [1]
- Trigger point injections (saline or local anesthetic): in ED settings, reduce pain by 2–3 points on a 10-point scale, reduce ED length of stay and opioid need [1]
- Aortic Dissection Detection Risk Score (ADD-RS): if dissection is in the differential [7]
14. ECG
- Not routinely indicated for isolated musculoskeletal LBP
- Obtain ECG when:
- Back pain is acute, severe, tearing, or associated with chest/abdominal pain
- Concern for aortic dissection (may show ST-T abnormalities in ~50% of type A dissections, most commonly ST depression or T-wave inversions) [19]
- ST elevation in aVR is associated with increased mortality in type A dissection [20]
- A normal ECG + normal troponin + elevated D-dimer pattern is a strong alerting triad for acute aortic syndrome rather than ACS [16]
- Rule out ACS as a cause of referred back pain
15. Assessment
- 80–90% of acute LBP is nonspecific and self-limited [1-2]
- Only 1–5% of primary care LBP presentations have a serious underlying pathology [11][21]
- Most common serious pathology: vertebral fracture (~4%), followed by malignancy (0.7%), infection (0.01%) [6][11]
- Typical presentation: axial pain, paraspinal muscle tenderness/spasm, no neurologic deficits, nonfocal exam
- Atypical features warranting further workup: night pain unrelieved by rest, progressive neurologic deficits, systemic symptoms, pain unresponsive to conservative measures after 4–8 weeks
- ~1/3 of patients transition from acute to chronic LBP over 6 months [1]
Severity stratification
- Mild: minimal functional limitation, able to perform ADLs
- Moderate: significant pain limiting activity, paraspinal spasm
- Severe: unable to ambulate, severe spasm, or any red flag features
16. Treatment Plan
Initial stabilization (ED)
- Reassurance regarding favorable prognosis [2-3]
- Advise to remain active and avoid bed rest [1][3]
Nonpharmacologic (first-line per ACP and VA/DoD guidelines): [1][3]
- Superficial heat (20 min several times daily) — moderate-quality evidence
- Acupuncture — slightly better than placebo and pharmacotherapy for pain reduction
- Dry needling — effective for myofascial trigger points
- Spinal manipulation — small effect on function (moderate-certainty evidence)
- Massage — small-to-moderate improvement
- TENS — reduces pain vs. placebo during/immediately after treatment
Pharmacologic: [1][3]
- NSAIDs (first-line): ibuprofen 400–600 mg q6–8h or naproxen 500 mg q12h
- Muscle relaxants (second-line): cyclobenzaprine 5–10 mg TID PRN (short course, sedation risk)
- Trigger point injections in ED: saline or lidocaine into myofascial trigger points
- Systemic corticosteroids: consider short course only for radicular pain
Do NOT use: acetaminophen, gabapentin, pregabalin, benzodiazepines, opioids (except acute traumatic injuries) [1]
Address modifiable risk factors for chronification: smoking cessation, weight loss, treat depression/anxiety, encourage physical activity [1]
17. Disposition
Discharge (vast majority)
Observation/admission criteria
- Intractable pain unresponsive to ED treatment
- Inability to ambulate
- Suspected cauda equina syndrome → emergent MRI and spine surgery consultation [1]
- Suspected spinal infection → MRI, blood cultures, IV antibiotics, ID consultation [1]
- Suspected malignancy with neurologic compromise
- Hemodynamic instability (consider AAA, aortic dissection)
Specialist consultation triggers
- Cauda equina syndrome → emergent spine surgery [1]
- Progressive or severe neurologic deficits → urgent neurosurgery/orthopedic spine
- Suspected malignancy → oncology
- Suspected infection → infectious disease
- Pain persisting >8 weeks despite conservative management → consider spine or pain specialist referral [1]
18. Follow Up / Return Precautions
Follow-up timing
- Primary care follow-up within 2–4 weeks if symptoms persist
- If no improvement by 8 weeks, pursue imaging (MRI) and laboratory evaluation [1]
- Screen for chronification risk using STarT Back or ODI at initial visit [1]
Return precautions — instruct patients to return immediately for:
- New or worsening leg weakness
- Bowel or bladder dysfunction (inability to urinate, incontinence)
- Saddle numbness (numbness in groin/buttock area)
- Fever or chills
- Unexplained weight loss
- Pain that is progressively worsening despite treatment
Patient counseling
- Most acute LBP resolves within 4–6 weeks [3]
- Staying active is better than bed rest [2-3]
- Minor flare-ups may occur over the subsequent year [22]
- Smoking cessation, weight management, and regular exercise reduce recurrence [1]
- Avoid catastrophizing language; reassure about the benign nature of nonspecific LBP [2]
References
1. Acute Low Back Pain: Diagnosis and Management. — Earwood JS, Doles NA, Russell RS. American Family Physician. 2025.
2. Nonspecific Low Back Pain. — Chiarotto A, Koes BW. The New England Journal of Medicine. 2022.
3. Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians. — Qaseem A, Wilt TJ, McLean RM, et al. Annals of Internal Medicine. 2017.
4. Low Back Pain. — Knezevic NN, Candido KD, Vlaeyen JWS, Van Zundert J, Cohen SP. Lancet. 2021.
5. Management of Low Back Pain: Guidelines From the VA/DoD. — Buelt A, McCall S, Coster J. American Family Physician. 2023.
6. Diagnosis and Treatment of Low Back Pain (LBP) (2022). — Maj Danielle Anderson DPT DSc OCS FAAOMPT, Thiru M. Annaswamy MD MA, LTC Adam J. Bevevino MD, et al Department of Veterans Affairs. 2022.
7. Acute Aortic Dissection. — Carrel T, Sundt TM, von Kodolitsch Y, Czerny M. Lancet. 2023.
8. Volume and Intensity of Walking and Risk of Chronic Low Back Pain. — Haddadj R, Nordstoga AL, Nilsen TIL, et al. JAMA Network Open. 2025.
9. Prognostic Factors for Pain Chronicity in Low Back Pain: A Systematic Review. — Nieminen LK, Pyysalo LM, Kankaanpää MJ. Pain Reports. 2020.
10. Evidence-Based Clinical Guidelines For Multidisciplinary Spine Care. — D. Scott Kreiner MD, Paul Matz MD, Daniel K. Resnick MD MS, et al American Academy of Pain Medicine (2020). 2020.
11. Non-Specific Low Back Pain. — Maher C, Underwood M, Buchbinder R. Lancet. 2017.
12. Musculoskeletal Low Back Pain in School-aged Children: A Review. — MacDonald J, Stuart E, Rodenberg R. JAMA Pediatrics. 2017.
13. Chronic Low Back Pain in Adults: Evaluation and Management. — Maharty DC, Hines SC, Brown RB. American Family Physician. 2024.
14. Herniated Lumbar Intervertebral Disk. — Deyo RA, Mirza SK. The New England Journal of Medicine. 2016.
15. Models of Care for Managing Non-Specific Low Back Pain. — Docking S, Sridhar S, Haas R, et al. The Cochrane Database of Systematic Reviews. 2025.
16. Acute Aortic Syndrome Revisited: JACC State-of-the-Art Review. — Vilacosta I, San Román JA, di Bartolomeo R, et al. Journal of the American College of Cardiology. 2021.
17. EACTS/STS Guidelines for Diagnosing and Treating Acute and Chronic Syndromes of the Aortic Organ. — Czerny M, Grabenwöger M, Berger T, et al. European Journal of Cardio-Thoracic Surgery : Official Journal of the European Association for Cardio-Thoracic Surgery. 2024.
18. ACR Appropriateness Criteria® Low Back Pain: 2021 Update. — Expert Panel on Neurological Imaging, Hutchins TA, Peckham M, et al. Journal of the American College of Radiology : JACR. 2021.
19. Frequency and Implication of ST-T Abnormalities on Hospital Admission Electrocardiograms in Patients With Type a Acute Aortic Dissection. — Kosuge M, Uchida K, Imoto K, et al. The American Journal of Cardiology. 2013.
20. Predictive Factors for Type a Aortic Dissection Mortality Based on Electrocardiogram Parameters and Clinical Presentations. — Rahmanian M, Bazrafshan M, Kamali F, et al. Journal of Electrocardiology. 2023.
21. Red Flags to Screen for Vertebral Fracture in Patients Presenting With Low-Back Pain. — Williams CM, Henschke N, Maher CG, et al. The Cochrane Database of Systematic Reviews. 2023.
22. Guideline Update: What's the Best Approach to Acute Low Back Pain?. — Bach SM, Holten KB. The Journal of Family Practice. 2009.