Acute low back pain is commonly treated by family physicians. In most cases, only conservative therapy is needed. However, the history and physical examination may elicit warning signals that indicate the need for further work-up and treatment. These "red flags" include a history of trauma, fever, incontinence, unexplained weight loss, a cancer history, long-term steroid use, parenteral drug abuse, and intense localized pain and an inability to get into a comfortable position. Treatment usually consists of nonsteroidal anti-inflammatory agents or acetaminophen and a gradual return to usual activities. Surgery is reserved for use in patients with severe neurologic deficits and, possibly, those with severe symptoms that persist despite adequate conservative treatment.