Lower Back Pain — Causes, Red Flags & Evidence-Based Treatment — Causes, Diagnosis & When to See a Doctor | MyMedicPlus

Lower back pain (LBP) is pain, muscle tension, or stiffness localised below the costal margin and above the inferior gluteal folds, with or without radiation into the legs. It affects the lumbar spine (L1-L5) and sacral area and is the leading single cause of disability globally, responsible for more years lived with disability than any other condition. Approximately 80% of adults will experience at least one significant episode during their lifetime. Acute LBP (lasting under six weeks) is very common and resolves spontaneously with conservative management in the majority of cases. Subacute LBP (six to twelve weeks) and chronic LBP (over twelve weeks) are more complex and require a biopsychosocial approach that addresses physical, psychological, and social contributors to the pain experience — including fear-avoidance beliefs, mood, sleep quality, and work factors. The vast majority of LBP is non-specific — no identifiable structural cause is found on imaging — and active management with exercise and reassurance produces better outcomes than passive treatments or prolonged rest.

Non-specific LBP (muscle strain, ligament sprain, or combined soft-tissue injury without identifiable structural cause) accounts for 85-90% of all presentations and generally carries an excellent prognosis. Specific structural causes include lumbar disc herniation (bulging or extruded disc material compressing nerve roots, causing radiculopathy or sciatica with pain radiating below the knee), lumbar spinal stenosis (narrowing of the spinal canal causing neurogenic claudication — bilateral leg pain, heaviness, or cramping relieved by sitting forward), spondylolisthesis (anterior slippage of one vertebra on another), and osteoporosis-related vertebral compression fractures (acute severe localised pain, particularly in older women after minor trauma). Inflammatory causes include ankylosing spondylitis and psoriatic spondyloarthritis (inflammatory back pain — worse with rest, better with exercise, morning stiffness over 60 minutes, onset under 45 years). Serious red flag causes include cauda equina syndrome (nerve root compression causing bladder or bowel dysfunction — surgical emergency), spinal metastases (primary lung, breast, prostate, renal), primary vertebral tumours, discitis, epidural abscess, and vertebral osteomyelitis.

Seek emergency care immediately for lower back pain accompanied by any change in bladder or bowel control — either retention (inability to urinate) or incontinence, and particularly the combination of urinary retention with overflow incontinence. These are signs of cauda equina syndrome (CES), which requires emergency MRI and surgical spinal decompression within 24-48 hours to prevent permanent paralysis and incontinence. Other CES features include saddle anaesthesia (numbness around the perineum, genitals, and inner thighs) and bilateral or progressive leg weakness. Also seek urgent evaluation for back pain with fever and rigors (possible spinal infection — discitis or epidural abscess), back pain after significant trauma or fall (vertebral fracture), back pain in a patient with known cancer, HIV, or who is immunocompromised, unexplained weight loss of more than 5% body weight with persistent back pain (possible spinal metastasis), or thoracic (mid-back) pain in older adults after minor trauma (osteoporotic fracture). Back pain in individuals under 20 or over 55 years with first onset also warrants closer investigation to exclude serious structural pathology.

Clinical examination includes neurological assessment of lower limb sensation in dermatomal distributions, muscle strength (hip flexion L1/2, knee extension L3/4, ankle dorsiflexion L4/5, plantar flexion S1), and deep tendon reflexes (knee jerk L3/4, ankle jerk S1). The straight leg raise test (SLR) — pain reproduced below 60 degrees of hip elevation — is sensitive for lumbar disc herniation with nerve root compression. Crossed SLR is highly specific. Routine X-ray is not needed for acute non-specific LBP without red flags — degenerative changes seen on imaging are poorly correlated with pain severity. MRI is the preferred imaging modality for suspected disc herniation with radiculopathy, cauda equina syndrome (urgent), spinal infection, malignancy, or neurogenic claudication. CT myelography is used when MRI is contraindicated. Blood tests including ESR, CRP, full blood count, and PSA in older men are ordered when infection, inflammation, or malignancy is suspected.

Stay active — bed rest is explicitly not recommended and worsens outcomes by increasing deconditioning, fear-avoidance, and chronicity risk. Heat application (heat wraps, hot water bottle) reduces acute muscle pain effectively and is preferred over cold for chronic LBP. Paracetamol provides modest analgesia; NSAIDs (ibuprofen, naproxen) are more effective for inflammatory LBP and radiculopathy; short-course muscle relaxants (diazepam, cyclobenzaprine) reduce acute spasm. Opioids are not recommended for chronic non-specific LBP. Physiotherapy with motor control exercises, McKenzie method, and manual therapy is the cornerstone of chronic LBP management and superior to passive treatments alone. Neuropathic pain medications — gabapentin or pregabalin — provide modest benefit for radiculopathic (sciatic) pain. Epidural corticosteroid injections provide temporary relief (four to twelve weeks) for acute radiculopathy but have no long-term benefit for non-specific LBP. Cognitive behavioural therapy (CBT) effectively addresses fear-avoidance beliefs, catastrophising, and depression that perpetuate chronic LBP. Surgery (lumbar discectomy for radiculopathy, decompressive laminectomy for stenosis) is reserved for significant neurological compromise unresponsive to six to twelve weeks of conservative treatment — for cauda equina syndrome, surgery is an emergency.

Strengthen core and lumbar stabilising muscles through regular exercise — walking, swimming, cycling, yoga, and Pilates are all effective and reduce recurrence rates. Specific lumbar stabilisation exercises supervised by a physiotherapist are the most evidence-based approach for recurrence prevention. Use correct lifting technique: bend at the knees, keep the load close to the body, do not twist the spine while lifting heavy objects, and avoid lifting heavy loads when fatigued. Maintain good posture and ergonomic workstation setup — monitor at eye level, chair height allowing feet flat on the floor, lumbar support. Take regular breaks from prolonged sitting — stand or walk for at least two minutes every 30-60 minutes. Maintain a healthy body weight, as each unit increase in BMI increases LBP risk. Quit smoking — nicotine impairs vertebral disc nutrition by reducing blood supply to disc tissue. Manage stress and psychological wellbeing, as psychological distress is a strong predictor of LBP chronicity.

Seek emergency care immediately for lower back pain with any change in bladder or bowel control, numbness in the saddle area (perineum, genitals, inner thighs), or sudden bilateral leg weakness — these are signs of cauda equina syndrome requiring emergency MRI and urgent surgery. Do not wait for a routine appointment if any of these symptoms are present. Seek urgent same-day or next-day assessment for back pain with fever and rigors (possible spinal infection), back pain following significant trauma, or severe unrelenting pain not responding to any position change or analgesics (possible vertebral fracture). Arrange an urgent appointment within one to two weeks for first-episode lower back pain with radiation below the knee and neurological symptoms (numbness, weakness, reflex changes), back pain with unexplained weight loss, or back pain in a known cancer patient. Routine review is appropriate for back pain present for more than four to six weeks without improvement on conservative care, for physiotherapy referral, or to discuss imaging. Most acute non-specific LBP improves significantly within two to four weeks — reassurance, activity maintenance, and simple analgesia are the mainstay of early management.