Introduction

Acute low back pain (LBP) is pain or discomfort localized between the lower rib margin and the gluteal folds, with or without radiation to the lower limbs, lasting less than 6 weeks. It is one of the most common musculoskeletal complaints worldwide and a leading cause of disability and healthcare utilization. Although numerous pathological conditions can cause low back pain, approximately 85–90% of cases are classified as non-specific low back pain, where no specific structural pathology is identified.

Most patients experience spontaneous improvement within several weeks with conservative management. However, clinicians must identify red flag features that suggest serious underlying conditions requiring urgent investigation and specialist referral.

Epidemiology

• One of the leading causes of disability worldwide.

• Lifetime prevalence approaches 60–80%.

• Most common between 30 and 60 years of age.

• Slightly more common among individuals performing manual labour or prolonged sedentary work.

• Most episodes resolve within 4–6 weeks, although recurrence is common.

Etiology

Non-specific low back pain (most common)

• Muscle strain

• Ligament sprain

• Fascial injury

• Mechanical overload

• Degenerative disc disease

• Facet joint dysfunction

Specific causes

• Lumbar disc herniation

• Lumbar spinal stenosis

• Vertebral compression fracture

• Spondylolisthesis

• Spondyloarthritis

• Vertebral osteomyelitis

• Epidural abscess

• Malignancy

• Osteoporosis-related fractures

• Cauda equina syndrome

• Referred pain from abdominal or pelvic pathology

Risk factors

• Increasing age

• Previous episodes of low back pain

• Heavy manual labour

• Repetitive lifting

• Obesity

• Physical inactivity

• Smoking

• Poor posture

• Prolonged sitting

• Psychological stress

• Depression and anxiety

• Occupational vibration exposure

Pathophysiology

Acute low back pain usually results from mechanical injury to the spinal muscles, ligaments, intervertebral discs, or facet joints following excessive loading or repetitive strain. Tissue injury triggers a local inflammatory response characterized by the release of prostaglandins, cytokines, and other inflammatory mediators that sensitize nociceptors and produce pain. Reflex paraspinal muscle spasm develops as a protective mechanism but may further increase pain and restrict movement. In some patients, lumbar nerve root compression due to disc herniation causes radicular pain (sciatica). Most mechanical injuries heal spontaneously within several weeks through resolution of inflammation and tissue repair.

Classification

According to symptom duration:

• Acute: less than 6 weeks

• Subacute: 6–12 weeks

• Chronic: more than 12 weeks

According to pain pattern:

• Non-specific mechanical low back pain

• Low back pain with radiculopathy (sciatica)

• Low back pain secondary to a specific spinal pathology

Clinical presentation

Patients commonly present with:

• Localized pain in the lumbar region

• Pain aggravated by movement

• Pain relieved by rest

• Muscle spasm

• Lumbar stiffness

• Reduced range of motion

• Difficulty bending or lifting

• Tenderness over paraspinal muscles

Patients with sciatica may additionally have:

• Pain radiating below the knee

• Buttock pain

• Numbness

• Tingling

• Positive straight-leg raise test

• Mild motor weakness in the affected nerve root distribution

Red flag signs

Urgent evaluation is required if any of the following are present:

• History of malignancy

• Unexplained weight loss

• Fever or systemic illness

• Night pain

• Recent significant trauma

• Osteoporosis

• Intravenous drug use

• Immunosuppression

• Persistent severe pain at rest

• Progressive neurological deficit

• Saddle anaesthesia

• New urinary retention or faecal incontinence

• Bilateral lower-limb weakness

• Suspected cauda equina syndrome

• Suspected spinal infection

• Suspected inflammatory back disease

Diagnostic criteria

Acute non-specific low back pain is diagnosed when all of the following are present:

• Pain localized between the lower ribs and gluteal folds

• Duration less than 6 weeks

• Mechanical pain pattern (worse with movement, improved by rest)

• No major neurological deficit

• No red flag features suggesting serious spinal pathology

• No alternative diagnosis explaining symptoms

Investigations

Patients without red flags

Routine investigations are not recommended.

Patients should be reassured that acute low back pain is usually self-limiting and imaging is unnecessary unless the findings would alter management.

Laboratory investigations (if infection, inflammatory disease, or malignancy is suspected)

• Complete blood count

• Erythrocyte sedimentation rate

• C-reactive protein

• Renal function tests

• Blood cultures (if infection is suspected)

Imaging

Plain X-ray

Indicated for:

• Trauma

• Suspected fracture

• Osteoporosis

• Persistent symptoms

• Structural deformity

MRI (preferred)

Indications include:

• Progressive neurological deficit

• Cauda equina syndrome

• Suspected spinal infection

• Malignancy

• Persistent radiculopathy

• Failure of conservative treatment

CT scan

Alternative when MRI is contraindicated or unavailable.

Differential diagnosis

• Lumbar muscle strain

• Lumbar disc herniation

• Sciatica

• Spinal stenosis

• Vertebral fracture

• Osteomyelitis

• Epidural abscess

• Ankylosing spondylitis

• Renal colic

• Pyelonephritis

• Abdominal aortic aneurysm

• Pancreatitis

• Hip osteoarthritis

• Metastatic spinal disease

Management

Treatment aims to:

• Relieve pain

• Restore function

• Maintain mobility

• Prevent chronicity

• Identify serious underlying disease

Non-pharmacological management

Patient education

Provide reassurance that most episodes improve within a few weeks.

Advise patients regarding:

• The benign nature of most acute low back pain

• Expected recovery

• Avoidance of prolonged bed rest

• Remaining active within pain limits

• Early return to normal activities and work as tolerated

Self-management

• Continue normal daily activities as symptoms improve.

• Avoid prolonged immobilization.

• Use local heat if helpful.

• Practice proper lifting techniques.

• Improve workplace ergonomics.

Exercise therapy

Once severe pain subsides, encourage:

• Walking

• Stretching exercises

• Core strengthening

• Aerobic exercise

• Individualized physiotherapy programmes

Pharmacological treatment

First-line NSAIDs

Ibuprofen

• 400 mg orally as an initial dose, then 200 mg every 8 hours

OR

Diclofenac sodium

• 50 mg orally every 8 hours for 7–14 days

OR

Meloxicam

• 7.5–15 mg orally every 12–24 hours for 7–14 days

Severe pain

Diclofenac

• 75 mg intramuscularly every 12 hours by deep IM injection for 1–3 days

±

Tramadol

• 100 mg intramuscularly every 12 hours by deep IM injection for 1–3 days

THEN

Diclofenac

• 50 mg orally every 8 hours for 7 days

±

Tramadol

• 50 mg orally every 8 hours for up to 7 days

Topical analgesics

May be added in patients with localized pain.

Diclofenac gel

• Apply every 12 hours

OR

Ketoprofen gel

• Apply every 12 hours

Gastroprotection

Patients with previous peptic ulcer disease or those requiring NSAIDs for 2 weeks or longer should receive gastroprotective therapy.

Omeprazole

• 20 mg orally once daily for 2 weeks or longer

OR

Pantoprazole

• 40 mg orally once daily for 2 weeks or longer

OR

Esomeprazole

• 40 mg orally once daily for 2 weeks or longer

OR

Lansoprazole

• 30 mg orally once daily for 2–4 weeks

Muscle relaxants

Baclofen

• Initially 5 mg orally every 8 hours

• Increase by 5 mg per dose every 3 days

• Maximum 20 mg every 8 hours

• Continue for up to 2 weeks

OR

Tizanidine

• Initially 2 mg orally every 8 hours

• Increase gradually by 2–4 mg every 1–4 days according to response

• Treatment may continue for 4 weeks or longer if required

• Discontinue gradually by reducing 2–4 mg daily to avoid withdrawal

Surgical management

Surgery is not indicated for uncomplicated acute non-specific low back pain.

Urgent surgical referral is indicated for:

• Cauda equina syndrome

• Progressive neurological deficit

• Spinal epidural abscess

• Unstable vertebral fracture

• Severe lumbar disc herniation causing persistent neurological impairment

• Spinal tumour causing cord or nerve compression

Rehabilitation

• Early mobilization

• Physiotherapy

• Core muscle strengthening

• Flexibility exercises

• Ergonomic education

• Occupational rehabilitation

• Gradual return to work and sporting activities

Monitoring and follow-up

Patients should be reviewed within 2–6 weeks to assess:

• Pain severity

• Functional improvement

• Return to normal activities

• Development of neurological symptoms

• Emergence of red flag features

Persistent pain beyond 6 weeks or worsening symptoms should prompt reassessment and consideration of further investigations or specialist referral.

Complications

• Chronic low back pain

• Recurrent episodes

• Lumbar radiculopathy

• Functional disability

• Reduced quality of life

• Work absenteeism

• Depression and anxiety

• Opioid dependence (if prolonged opioid therapy is used)

Prevention

• Regular physical activity

• Core strengthening exercises

• Maintenance of healthy body weight

• Correct lifting techniques

• Workplace ergonomic modifications

• Smoking cessation

• Avoid prolonged sitting

• Early management of recurrent episodes

• Patient education regarding back care

Prognosis

The prognosis is generally excellent. Approximately 80–90% of patients with acute non-specific low back pain experience substantial improvement within 4–6 weeks with conservative management. Recurrence is common, but most recurrent episodes also resolve without long-term disability. Poor prognostic factors include persistent psychosocial stressors, physical inactivity, obesity, smoking, and failure to remain active during recovery.