In the common presentation of acute low back pain, pain develops after movements that involve lifting, twisting, or forward-bending. The symptoms may start soon after the movements or upon waking up the following morning. The description of the symptoms may range from tenderness at a particular point to diffuse pain. It may or may not worsen with certain movements, such as raising a leg, or positions, such as sitting or standing. Pain radiating down the legs (known as sciatica) may be present. The first experience of acute low back pain is typically between the ages of 20 and 40. This is often a person's first reason to see a medical professional as an adult. Recurrent episodes occur in more than half of people with the repeated episodes being generally more painful than the first.
Emerging technologies such as X-rays gave physicians new diagnostic tools, revealing the intervertebral disc as a source for back pain in some cases. In 1938, orthopedic surgeon Joseph S. Barr reported on cases of disc-related sciatica improved or cured with back surgery. As a result of this work, in the 1940s, the vertebral disc model of low back pain took over, dominating the literature through the 1980s, aiding further by the rise of new imaging technologies such as CT and MRI. The discussion subsided as research showed disc problems to be a relatively uncommon cause of the pain. Since then, physicians have come to realize that it is unlikely that a specific cause for low back pain can be identified in many cases and question the need to find one at all as most of the time symptoms resolve within 6 to 12 weeks regardless of treatment.
2016 — More editing, more! Added some better information about pain being a poor indicator, and the role of myofascial trigger points. This article has become extremely busy in the last couple months — about 4,000 readers per day, as described here — so I am really polishing it and making sure that it’s the best possible answer to people’s fears about back pain.
If low back pain gets worse or does not improve after two to three days of home treatment, contact a primary-care physician. The physician can evaluate the patient and perform a neurological exam in the office to determine which nerve root is being irritated, as well as rule out other serious medical conditions. If there are clear signs that the nerve root is being compressed, a physician can prescribe medications to relieve the pain, swelling and irritation; he or she also may recommend limitation of activities. If these treatment options do not provide relief within two weeks, it may be time to consider other diagnostic studies and possibly surgery.