What is the diagnosis and treatment for a male in his 40s with acute back pain after lifting a heavy box, without symptoms of numbness, weakness, or bladder and bowel incontinence?

Acute Nonspecific Low Back Pain (Lumbar Strain)

Diagnosis

This is acute nonspecific low back pain (lumbar strain) from lifting a heavy box—a self-limited musculoligamentous injury with excellent prognosis. 1, 2

The absence of numbness, weakness, or bowel/bladder dysfunction rules out serious pathology requiring urgent intervention:

• No red flags present: No signs of cauda equina syndrome (which would include urinary retention/incontinence, bilateral leg weakness, saddle anesthesia), radiculopathy (no radiating leg pain below the knee, no sensory deficits), fracture, infection, or malignancy 1, 2, 3
• Mechanism consistent with mechanical injury: Lifting a heavy object causes musculoligamentous strain without structural damage in the vast majority of cases 4, 5
• No imaging needed: Without red flags, diagnostic imaging and laboratory testing are not required and should be delayed for at least 4-6 weeks if symptoms persist 2, 3, 5

Treatment Algorithm

First-Line: Self-Care + NSAIDs

Start with NSAIDs as the preferred first-line medication, providing small to moderate pain relief. 6

• NSAIDs: Ibuprofen 400-600 mg every 6-8 hours or naproxen 500 mg twice daily, prescribed at the lowest effective dose for the shortest period necessary 6
• Acetaminophen alternative: Up to 4 grams daily can be used if NSAIDs are contraindicated, though evidence shows no significant difference from placebo for pain intensity 6
• Assess cardiovascular and GI risk: Before prescribing NSAIDs, evaluate for cardiovascular disease, GI bleeding history, renal impairment, and hypertension 6

Critical Self-Care Measures

Advise the patient to remain active and avoid bed rest—activity restriction prolongs recovery and delays return to normal function. 6, 2, 3

• Stay active: Continue normal activities as tolerated, including work with modifications if needed 6, 3, 5
• Apply heat: Use heating pads or heated blankets for short-term symptomatic relief 6
• No bed rest: Bed rest provides no benefit and should be avoided entirely 6, 2

Second-Line: Add Muscle Relaxant if Severe Pain Persists

If pain remains severe after 2-4 days despite NSAIDs and self-care, add a skeletal muscle relaxant for short-term use (≤1-2 weeks). 6

• Cyclobenzaprine 5-10 mg three times daily is the preferred agent based on the largest body of evidence showing superiority to placebo for short-term global improvement 6, 7
• Warning: All muscle relaxants cause central nervous system adverse effects, primarily sedation, drowsiness, and dizziness 6, 7
• Time-limited only: No evidence supports efficacy beyond 2 weeks; do not prescribe for chronic use 7

Third-Line: Consider Spinal Manipulation

For patients who do not improve with medications and self-care after 1-2 weeks, spinal manipulation by appropriately trained providers (chiropractor, osteopath, physical therapist) provides small to moderate short-term benefits. 1, 6

Treatments to AVOID

• No systemic corticosteroids: Not effective for acute low back pain with or without sciatica 1, 6, 7
• No supervised exercise therapy: Not effective for acute low back pain (duration <4 weeks); optimal timing to start exercise is unclear but suggested after 2-6 weeks 1
• Avoid opioids unless absolutely necessary: Only consider tramadol or opioids for severe, disabling pain uncontrolled by NSAIDs and acetaminophen, due to substantial risks of abuse, addiction, and aberrant drug-related behaviors 6

Expected Course and Follow-Up

• Natural history: Most episodes of acute nonspecific low back pain are self-limited and resolve within 4-6 weeks 2, 3, 5
• Reassess at 2-4 weeks: If symptoms are not improving, consider physical therapy referral for McKenzie method or spine stabilization exercises 2
• Red flag monitoring: Instruct the patient to return immediately if new symptoms develop: leg weakness, numbness, bowel/bladder dysfunction, or progressive neurologic deficits 2, 3

Common Pitfalls to Avoid

• Do not order imaging initially: X-rays, MRI, or CT are unnecessary without red flags and often show degenerative changes that correlate poorly with symptoms 1, 2, 3
• Do not prescribe extended medication courses: Reserve prolonged use only for patients showing clear continued benefits without major adverse events 1, 6
• Do not recommend bed rest: This is harmful and delays recovery 6, 2, 3
• Do not use muscle relaxants chronically: No evidence for efficacy beyond 2 weeks, and risks include tolerance and dependence 7