Pain in the back that lasts just for a few days or just for a few weeks is considered acute, or short-term. It is common for back pain to be acute. In most cases, it resolves on its own within a few days with self-care, and there is no residual functional loss. Many times, symptom disappearance requires a few months of time.   The term chronic back pain refers to back pain that persists after undergoing treatment for an initial injury or underlying cause of acute back pain for at least 12 weeks. One year after suffering acute back pain, approximately 20 percent of patients develop chronic back pain. The persistence of pain does not always indicate an underlying medical problem or one that can be easily identified and treated. Medical and surgical treatment can relieve chronic back pain in some cases, but the pain may persist in others.