In some cases, the cause of back pain remains mysterious despite exams and medical tests. In part, that’s because everyone is different—problems that cause severe back pain in one person can cause no symptoms at all in another person. Most back pain causes aren’t serious or life threatening. Although in rare cases, back pain can signal a more severe medical problem. Here are the most common potential culprits. 1. Too Much, Too Soon Your back may ache after your first workout in a while or a day of aggressive snow shoveling or yard work. In these cases, you may have pulled or strained a muscle or ligament in your back. Movements that involve bending, lifting or twisting are among the most likely to trigger back pain. But even too much sitting can lead to discomfort. Back pain from overuse usually resolves on its own within a few days. Applying warm compresses and gentle stretching can help you recover from back muscle strains. 2. Disc Injuries or Degeneration As you age, the flat, round discs that fit between each vertebra break down. You may feel pain as they lose their cushioning ability and one backbone rubs against another. Doctors call this degenerative disc disease. Sometimes, the jelly-like filling squeezes out of the hard outer coating of the disc, a condition called a herniated disc. The pressure of fluid against the outer ring can cause lower back pain, while leaked fluid can irritate nearby nerves, causing discomfort that runs down one or both legs. 3. Alignment Problems Scoliosis, an abnormal curve in your spine, often develops during childhood or teenage years. But it may not cause pain until middle age or later, when it begins to place increasing pressure on the nerves within your spinal cord. A condition called degenerative spondylolisthesis occurs when the ligaments holding your spine in place wear down over time. Bones in your back can slip out of the proper position, sliding forward until one extends over the top of another. The condition becomes painful when the bones begin to compress the spinal nerves. Alignment problems don’t always begin in your back. Pain or deformities in your foot or ankle can change the way you walk, stretching ligaments and tendons beyond their normal range. Pain and arthritis that reaches into your lower back can follow. 4. Fractures You can break a vertebra during a fall or other accident. But most commonly, fractures develop as a result of the bone-thinning disease osteoporosis. Over time, your vertebrae can crumble, which can cause moderate to severe back pain when you move or when bones compress nerves. 5. Infections and Tumors Rare, but serious, infections can strike the vertebrae, a condition called osteomyelitis. Or, you can develop diskitis (discitis), inflammation in the discs between the bones. The swelling that results can send pain signals up your spinal cord to your brain. Cancer is also uncommon but can cause pain when tumors form along the spinal cord. Some cancers begin in the back, but most often they form when cancer from elsewhere in the body spreads. If you have back pain and a history of cancer—or other concerning symptoms, such as unexplained weight loss—your doctor may quickly order imaging tests to spot tumors. 6. Health Issues in Other Parts of Your Body Conditions that affect other organs—not just the muscles and joints in your back—can cause pain in or near your lower back. These include kidney stones or infections, pancreatitis, sexually transmitted infections, and endometriosis, in which the tissue that lines the uterus grows elsewhere in the body. Pregnant women frequently develop back pain, and so do people with fibromyalgia, which causes fatigue and muscle aches throughout the body. 7. Spinal Stenosis If you have degenerative disc disease, the mechanical loading on your vertebrae shift. Your spine may respond by developing new bone where excess force is applied. These bone growths (osteophytes) can squeeze the nerves in your spinal cord, resulting in pain in your back or pain and numbness running down your legs. Often, this condition impairs your ability to walk and requires surgical treatment.