Acute low back pain with or without sciatica usually is self-limited and has no serious underlying pathology. For most patients, reassurance, pain medications, and advice to stay active are sufficient. A more thorough evaluation is required in selected patients with "red flag" findings associated with an increased risk of cauda equina syndrome, cancer, infection, or fracture. These patients also require closer follow-up and, in some cases, urgent referral to a surgeon. In patients with nonspecific mechanical low back pain, imaging can be delayed for at least four to six weeks, which usually allows the pain to improve. There is good evidence for the effectiveness of acetaminophen, nonsteroidal anti-inflammatory drugs, skeletal muscle relaxants, heat therapy, physical therapy, and advice to stay active. Spinal manipulative therapy may provide short-term benefits compared with sham therapy but not when compared with conventional treatments. Evidence for the benefit of acupuncture is conflicting, with higher-quality trials showing no benefit. Patient education should focus on the natural history of the back pain, its overall good prognosis, and recommendations for effective treatments.