In most episodes of low back pain, a specific underlying cause is not identified or even looked for, with the pain believed to be due to mechanical problems such as muscle or joint strain. If the pain does not go away with conservative treatment or if it is accompanied by "red flags" such as unexplained weight loss, fever, or significant problems with feeling or movement, further testing may be needed to look for a serious underlying problem. In most cases, imaging tools such as X-ray computed tomography are not useful and carry their own risks. Despite this, the use of imaging in low back pain has increased. Some low back pain is caused by damaged intervertebral discs, and the straight leg raise test is useful to identify this cause. In those with chronic pain, the pain processing system may malfunction, causing large amounts of pain in response to non-serious events.
Initial management with non–medication based treatments is recommended. NSAIDs are recommended if these are not sufficiently effective. Normal activity should be continued as much as the pain allows. Medications are recommended for the duration that they are helpful. A number of other options are available for those who do not improve with usual treatment. Opioids may be useful if simple pain medications are not enough, but they are not generally recommended due to side effects. Surgery may be beneficial for those with disc-related chronic pain and disability or spinal stenosis. No clear benefit has been found for other cases of non-specific low back pain. Low back pain often affects mood, which may be improved by counseling or antidepressants. Additionally, there are many alternative medicine therapies, including the Alexander technique and herbal remedies, but there is not enough evidence to recommend them confidently. The evidence for chiropractic care and spinal manipulation is mixed.
Approximately 9 to 12% of people (632 million) have LBP at any given point in time, and nearly 25% report having it at some point over any one-month period. About 40% of people have LBP at some point in their lives, with estimates as high as 80% among people in the developed world. Difficulty most often begins between 20 and 40 years of age. Men and women are equally affected. Low back pain is more common among people aged 40–80 years, with the overall number of individuals affected expected to increase as the population ages.
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.
Other problems may occur along with low back pain. Chronic low back pain is associated with sleep problems, including a greater amount of time needed to fall asleep, disturbances during sleep, a shorter duration of sleep, and less satisfaction with sleep. In addition, a majority of those with chronic low back pain show symptoms of depression or anxiety.
Low back pain is not a specific disease but rather a complaint that may be caused by a large number of underlying problems of varying levels of seriousness. The majority of LBP does not have a clear cause but is believed to be the result of non-serious muscle or skeletal issues such as sprains or strains. Obesity, smoking, weight gain during pregnancy, stress, poor physical condition, poor posture and poor sleeping position may also contribute to low back pain. A full list of possible causes includes many less common conditions. Physical causes may include osteoarthritis, degeneration of the discs between the vertebrae or a spinal disc herniation, broken vertebra(e) (such as from osteoporosis) or, rarely, an infection or tumor of the spine.
Women may have acute low back pain from medical conditions affecting the female reproductive system, including endometriosis, ovarian cysts, ovarian cancer, or uterine fibroids. Nearly half of all pregnant women report pain in the lower back or sacral area during pregnancy, due to changes in their posture and center of gravity causing muscle and ligament strain.