GRADE A RECOMMENDATIONS (based on good-quality patient-oriented evidence): Advise patients to stay active and continue ordinary activity within the limits permitted by pain, avoid bed rest, and return to work early, which is associated with less disability. Consider McKenzie exercises, which are helpful for pain radiating below the knee. Recommend acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) if medication is necessary. COX-2 inhibitors, muscle relaxants, and opiate analgesics have not been shown to be more effective than NSAIDs for acute low back pain. Consider imaging if patients have no improvement after 6 weeks, although diagnostic tests or imaging is not usually required. GRADE B RECOMMENDATIONS (based on inconsistent or limited-quality patient-oriented evidence): Reassure patients that 90% of episodes resolve within 6 weeks-regardless of treatment. Advise patients that minor flares-ups may occur in the subsequent year. Consider a plain lumbosacral spine x-ray if there is suspicion of spinal fracture or compression. Consider a bone scan after 10 days, if fracture is still suspected or the patient has multiple sites of pain. Suspect cauda equina syndrome or severe or progressive neurological deficit if red flags are present. Obtain complete blood count, urinalysis, and sedimentation rate if cancer or infection are possibilities. If still suspicious, consider referral or perform other studies. Remember that a negative plain film x-ray does not rule out disease. GRADE C RECOMMENDATIONS (based on consensus, usual practice, opinion, disease-oriented evidence, or case series): Recommend ice for painful areas and stretching exercises. Discuss the use of proper body mechanics and safe back exercises for injury prevention. Refer for goal-directed manual physical therapy if there is no improvement in 1 to 2 weeks, not modalities such as heat, traction, ultrasound, or transcutaneous electrical nerve stimulation. Do not refer for surgery in the absence of red flags.