Atraumatic back pain is a common condition affecting a significant portion of adults. Approximately 80% of individuals will experience it during their lifetime, making it a frequent reason for primary care and emergency visits. In the United States, about 4.4 million emergency department (ED) visits in 2021 were due to back pain, representing 2% to 4% of all ED visits. While most cases are benign, serious spinal pathologies occur in 2.5% to 5.1% of ED presentations, requiring prompt diagnosis and management. This review categorizes causes into emergent, “worst first” conditions and less urgent, yet sometimes still critical, etiologies.