Lower back pain is the single leading cause of disability worldwide, affecting approximately 619 million people at any given time and costing the US economy over $100 billion annually in lost productivity and healthcare. It is also one of the top reasons for doctor visits, emergency room presentations, and — unfortunately — opioid prescriptions. The overwhelming majority of lower back pain episodes resolve within 4–6 weeks with appropriate conservative care, yet many patients undergo imaging and interventions that are not only unnecessary but may worsen outcomes by medicalising a self-limiting condition.
Why Your Back Hurts: Common Causes
Muscle Strain and Ligament Sprain (Non-Specific Low Back Pain)
Approximately 85% of lower back pain has no identifiable specific structural cause on imaging. It arises from muscle or ligament strain, often triggered by lifting, twisting, sudden movements, or prolonged poor posture. The muscles of the lumbar region are dense and metabolically active; when strained, they spasm, producing intense pain that is typically worse with movement and relieved partially by rest. This type of pain generally resolves within 2–6 weeks.
Disc Herniation (Slipped Disc)
Intervertebral discs act as shock absorbers between vertebrae. When the outer fibrous ring (annulus fibrosus) tears, the soft inner nucleus pulposus can protrude and compress adjacent nerve roots. If a herniated disc compresses the sciatic nerve, it produces sciatica: sharp, burning pain radiating from the lower back through the buttock and down the leg, often to the foot. Herniated discs are most common at L4-L5 and L5-S1 levels. The majority (90%+) resolve with conservative management within 12 weeks.
Spinal Stenosis
Age-related narrowing of the spinal canal compresses the spinal cord or nerve roots, causing neurogenic claudication: leg pain and weakness that worsens with walking or standing and is relieved by sitting or bending forward (the characteristic "shopping cart sign"). It predominantly affects adults over 60.
Degenerative Disc Disease
A misleading name for the normal age-related process of disc desiccation and height loss, visible on MRI. Many people with severely "degenerated" discs on imaging have no pain; conversely, many people with significant pain have minimal imaging findings. MRI findings should always be interpreted in clinical context.
Red Flags: When Back Pain Is an Emergency
Seek immediate medical attention if back pain is accompanied by:
- Bowel or bladder incontinence or retention (possible cauda equina syndrome — a surgical emergency)
- Numbness in the inner thighs or genitals ("saddle anaesthesia")
- Fever and night sweats (possible spinal infection or malignancy)
- Unexplained weight loss
- Worsening pain that is severe and constant, particularly at night
- History of cancer
- Recent significant trauma
Evidence-Based Treatment
Stay Active
Bed rest is actively harmful for acute low back pain — it delays recovery and worsens outcomes. Continuing normal activities as tolerated, or returning to them as quickly as possible, consistently outperforms bed rest in clinical trials.
Exercise
Core strengthening exercises, yoga, Pilates, and aquatic therapy all have evidence for both acute and chronic low back pain. The specific type matters less than consistency. Exercise is the single most effective long-term intervention for chronic low back pain, reducing both pain intensity and disability.
Medications
NSAIDs (ibuprofen, naproxen) are the first-line medication for acute low back pain — they provide modest but consistent pain relief. Muscle relaxants add limited benefit for acute spasm. Opioids are not recommended for acute non-specific low back pain given poor evidence, significant addiction risk, and worse long-term outcomes. For chronic pain, tricyclic antidepressants and duloxetine have evidence.
Physical Therapy and Manual Therapy
Spinal manipulation (chiropractic or osteopathic) provides short-term relief for acute low back pain comparable to NSAIDs. Physical therapy focused on progressive exercise and patient education produces superior long-term outcomes to passive modalities alone.
Sources
- GBD 2019 Collaborators. Global Burden of Disease. Lancet. 2020.
- Qaseem A, et al. Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain. Ann Intern Med. 2017.
- Chou R, et al. Diagnosis and Treatment of Low Back Pain. Ann Intern Med. 2007.
- Mayo Clinic. Back pain — Diagnosis and treatment. 2023.