Back Pain — Causes, Red Flags, Diagnosis & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Back pain is one of the most common and disabling medical conditions worldwide, affecting an estimated 619 million people and constituting the leading cause of years lived with disability globally. Approximately 80% of adults experience at least one episode of significant back pain during their lifetime. The vast majority — 95% — is non-specific or mechanical back pain with no identifiable serious pathological cause: the pain arises from strain of muscles, ligaments, facet joints, or intervertebral discs without structural nerve compression or systemic disease. Acute mechanical low back pain typically resolves within 4-6 weeks in most patients. However, 10-15% develop chronic back pain (lasting more than 3 months), and 2-7% become significantly disabled. The remaining 5% of back pain cases involve serious pathology — fracture, infection, malignancy, inflammatory spondyloarthritis, or neurological emergency (cauda equina syndrome) — which must be identified promptly using 'red flag' screening.

Mechanical causes (95%): non-specific muscle or ligament strain (most common — sudden twisting, lifting); lumbar disc herniation (prolapsed intervertebral disc pressing on nerve root — causes radiculopathy: shooting pain, numbness, weakness in the leg — 'sciatica'); lumbar spondylosis (degenerative disc disease and osteoarthritis of facet joints); spinal stenosis (narrowing of spinal canal — typically causes neurogenic claudication: bilateral leg pain on walking, relieved by sitting or flexion); spondylolisthesis (forward slip of one vertebra over another); and sacroiliac joint dysfunction. Serious causes (5%): vertebral fracture (osteoporotic — postmenopausal, steroid use; traumatic); spinal infection (vertebral osteomyelitis, epidural abscess — fever, elevated CRP, risk factors: IV drug use, diabetes, recent spine procedure); spinal malignancy (metastases — breast, prostate, lung; multiple myeloma; primary bone tumour); cauda equina syndrome (central disc prolapse compressing nerve roots — bilateral leg weakness, saddle anaesthesia, bladder/bowel dysfunction); inflammatory back pain (axial spondyloarthritis/ankylosing spondylitis — younger patients, morning stiffness greater than 45 minutes, improvement with exercise). Psychosocial risk factors ('yellow flags') for chronification: fear-avoidance beliefs, catastrophising, depression, work dissatisfaction, and manual occupation.

Mechanical back pain: dull aching or sharp low back pain worsened by movement and relieved by rest; may radiate to buttocks or upper thighs; associated with muscle spasm and stiffness, particularly in the morning or after prolonged sitting. Nerve root compression (radiculopathy/sciatica): lancinating, electric, or burning pain radiating down the leg below the knee following a dermatomal distribution (L4: medial calf; L5: dorsum of foot; S1: lateral foot and sole); associated with paraesthesia, numbness, and weakness. Straight leg raise test positive (Lasegue sign) at below 60 degrees in L4-L5-S1 disc herniation. Red flags requiring urgent investigation (within 24-48 hours) — possible serious pathology: age below 20 or above 55 with new onset back pain; pain that is constant, progressive, and unrelated to movement; night pain waking from sleep; fever or unexplained weight loss; history of cancer; immunosuppression; IV drug use; progressive neurological deficit (leg weakness, sensory loss); saddle anaesthesia (perianal/perineal numbness); urinary retention or incontinence — EMERGENCY (cauda equina syndrome).

Most acute mechanical back pain requires NO investigation — clinical diagnosis is sufficient for typical presentations without red flags. NICE recommends against routine X-ray for non-specific low back pain (radiation exposure, findings poorly correlate with symptoms). Investigations when red flags are present: MRI lumbar spine (best for disc herniation, stenosis, cauda equina, infection, malignancy); CT for bony detail (fracture, spondylolisthesis); bone scan or PET-CT for metastatic disease; blood tests: ESR, CRP (elevated in infection, malignancy, inflammatory disease), FBC, calcium, protein electrophoresis (myeloma), PSA (prostate cancer). For suspected axial spondyloarthritis: HLA-B27, sacroiliac joint MRI (earliest change — bone marrow oedema). EMG/nerve conduction studies for chronic radiculopathy characterisation.

Acute non-specific back pain: the most important message is to remain active — bed rest worsens outcomes; continue normal activities as able. First-line: NSAIDs (ibuprofen 400 mg TDS or naproxen 500 mg BD with food) for up to 7-14 days — more effective than paracetamol. Topical NSAIDs (diclofenac gel) for localised pain. Weak opioids (codeine) for short-term use only if NSAIDs insufficient. Heat application. Short-term physiotherapy (manual therapy — spinal manipulation, mobilisation) effective for acute/subacute pain. Muscle relaxants (diazepam — short course only — for severe spasm). Chronic back pain (more than 3 months): NICE recommends exercise therapy as first-line (supervised group exercise — yoga, Pilates, aerobic exercise); psychological therapy — cognitive behavioural therapy (CBT) for pain catastrophising and fear-avoidance; multidisciplinary pain rehabilitation programmes; acupuncture has limited evidence (available on NHS for chronic primary pain). Epidural corticosteroid injection for acute disc herniation with radiculopathy unresponsive to conservative measures — short-term benefit. Surgery: microdiscectomy for disc herniation with severe radiculopathy not resolving after 6-8 weeks of conservative management; spinal decompression (laminectomy) for neurogenic claudication from spinal stenosis — reserved for significant disability; spinal fusion — limited evidence for non-specific back pain.

Cauda equina syndrome — compression of the cauda equina nerve roots from central disc herniation — causes bladder and bowel incontinence, saddle anaesthesia, and bilateral leg weakness. This is a neurosurgical emergency requiring decompression within 24-48 hours to prevent permanent paralysis. Spinal cord compression from vertebral metastases or fractures also causes irreversible paralysis without urgent treatment (dexamethasone and radiotherapy). Chronic back pain is strongly associated with depression (3x higher prevalence), anxiety, sleep disturbance, and opioid dependence. Foot drop from unresolved L4/5 nerve compression causes persistent gait abnormality. Occupational back pain is the leading cause of work-related disability in high-income countries.

Regular exercise is the most evidence-based preventive measure — core strengthening (Pilates, yoga), swimming, and walking reduce recurrence risk by 30-40%. Maintain a healthy BMI — each unit increase in BMI increases back pain risk by approximately 10%. Ergonomic workstation setup: monitor at eye level, chair supporting lumbar curve, feet flat on floor, keyboard at elbow height; avoid prolonged static sitting — stand or walk for 2-3 minutes every 30-60 minutes. Correct manual handling technique: bend at knees (not waist) when lifting, hold load close to body, avoid twisting while bearing load. Stop smoking — smokers have higher back pain rates (nicotine impairs disc nutrition via microvascular damage). For osteoporotic fracture prevention: calcium 1000-1200 mg daily, vitamin D 800-1000 IU daily, and bisphosphonates in high-risk individuals.

Call emergency services (999/911) or attend Emergency Department immediately for: any loss of bladder or bowel control; sudden inability to pass urine (urinary retention); numbness or tingling in the perineum, inner thighs, or buttocks (saddle anaesthesia); rapidly progressive leg weakness or paralysis — these are symptoms of cauda equina syndrome, a surgical emergency requiring urgent MRI and spinal decompression. See your GP urgently (within 24-48 hours) for: back pain with fever and/or unexplained weight loss; back pain in anyone with known cancer; pain that is constant, severe, and unrelated to movement; new significant neurological symptoms (foot drop, progressive leg weakness). Routine GP review for: back pain not improving after 4-6 weeks of self-management; back pain in anyone under 20 or over 55 with no prior similar episode.