Back pain is the leading cause of disability worldwide, affecting an estimated 619 million people in 2020 alone. Most of the time, it means you’ve strained a muscle or irritated a joint through everyday movement, poor posture, or overexertion. Less commonly, it signals a disc problem, nerve compression, or even an issue with an internal organ like your kidneys. Understanding the type, location, and behavior of your pain can help you figure out what’s going on and whether you need to act quickly.
Muscle Strains and Ligament Sprains
The most common reason your back hurts is a simple soft tissue injury. A strain happens when the muscles or tendons supporting your spine get pulled, twisted, or torn. A sprain involves the ligaments, the bands of tissue that hold your vertebrae together and prevent excessive movement at the joints. Both feel similar: a dull ache or stiffness across the lower back, sometimes with muscle spasms, that gets worse with certain movements and better with rest.
These injuries typically happen from lifting something heavy with poor form, twisting awkwardly, sitting in one position for hours, or even sleeping in a bad position. The good news is that most people with a lumbar strain or sprain recover fully within about two weeks. If your symptoms persist longer than that, it may be worth looking into other causes.
Disc Problems
Between each vertebra sits a rubbery disc that acts as a shock absorber. These discs can bulge or herniate, and the distinction matters. A bulging disc is like a hamburger patty that’s too wide for its bun: the outer layer puffs out, usually affecting a quarter to half the disc’s circumference, but nothing leaks out. A herniated disc involves a crack in that tough outer layer, allowing softer inner material to push through.
Herniated discs are more likely to cause pain than bulging ones. The material that pushes out can press directly on a nearby nerve root, but more commonly it triggers inflammation around the nerve, which is what produces the sharp, burning, or shooting pain. You might feel this pain not just in your back but radiating down into your buttock and leg, especially if the herniation is in the lower spine.
Nerve-Related Pain and Sciatica
When a disc, bone spur, or narrowed spinal canal presses on a nerve root in your lower back, the result is radiculopathy. The most well-known form is sciatica, which involves compression of the sciatic nerve, the longest nerve in your body. It runs from the lower back down the back of each leg.
Sciatica has a distinct feel. Rather than a generalized ache, you get pain that travels along a specific path, often shooting from your lower back through your buttock and down the back of one leg. It can come with numbness, tingling, or a pins-and-needles sensation. Some people notice weakness in the affected leg, making it harder to push off while walking or lift the foot. The pain is usually worse on one side and often intensifies when you sit, cough, or sneeze.
Upper and Middle Back Pain
Pain in the upper back (the thoracic spine, roughly between the base of your neck and the bottom of your rib cage) has a different set of common causes than lower back pain. Poor posture is the biggest contributor, especially from prolonged sitting at a desk or looking down at a phone. The muscles between your shoulder blades fatigue and tighten, creating a persistent ache.
Injuries to the rear segments of the ribs or the shoulder blades, which anchor to the upper back, can also cause pain in this area. Sports injuries and repetitive strain from hobbies or work are frequent culprits. Upper back pain is less likely to involve disc herniations than the lower back, because the thoracic spine is more rigid and supported by the rib cage.
Age-Related Spinal Changes
As you get older, the spinal canal can gradually narrow, a condition called spinal stenosis. This narrowing compresses the nerves and blood vessels running through the spine. The hallmark symptom is pain or heaviness in the legs that gets worse with walking or standing and improves when you sit down or lean forward, like over a shopping cart. This postural relief is a key feature that distinguishes it from circulation problems in the legs, which can feel similar.
A related condition, degenerative spondylolisthesis, occurs when one vertebra slips forward over the one below it. This usually happens at the L4/L5 level in people over 40. The slippage functionally narrows the spinal canal, producing symptoms that overlap heavily with stenosis: activity-related back and leg pain, weakness, and sometimes changes in gait. In severe cases of either condition, bowel or bladder function can be affected.
When Back Pain Isn’t From Your Back
Sometimes what feels like back pain actually originates from an internal organ. Kidney stones are a common example. The pain tends to be focused on one side of the lower back, underneath the ribs, rather than across the center. It comes in waves, changing intensity as the stone moves through the urinary tract, and it doesn’t improve when you shift positions. Musculoskeletal back pain, by contrast, usually responds to movement and position changes.
Kidney stone pain often starts high, near the kidney, then migrates toward the abdomen and eventually the groin. It can be accompanied by blood in the urine (sometimes visible, sometimes only detectable on a test), painful or frequent urination, nausea, vomiting, and cloudy or foul-smelling urine. Fever and chills alongside back pain can indicate an infection and need prompt attention. If your back pain comes with any of these urinary symptoms, the cause may not be your spine at all.
Acute, Subacute, and Chronic Pain
Doctors categorize back pain by how long it lasts. Acute back pain is anything under six weeks. Subacute pain lasts six to twelve weeks. Persistent (often called chronic) back pain continues for twelve weeks or longer. These categories matter because they guide what kind of evaluation and treatment makes sense.
Most acute back pain resolves on its own. Current guidelines from the American Academy of Family Physicians recommend against imaging like MRIs or X-rays during the first six weeks unless red flags are present. That’s because imaging often reveals findings, like minor disc bulges, that look alarming but are extremely common in people with no pain at all. Imaging is generally reserved for cases where conservative approaches have failed and a procedure like an injection or surgery is being considered.
Signs That Need Immediate Attention
A small number of back pain cases involve something serious that requires emergency care. Cauda equina syndrome occurs when the bundle of nerves at the base of the spinal cord becomes severely compressed. Symptoms include lower back pain combined with numbness in the inner thighs, buttocks, or groin area (sometimes called “saddle” numbness because it covers the areas that would touch a saddle). Difficulty urinating or having a bowel movement, loss of bladder or bowel control, and sudden weakness in one or both legs are all emergency symptoms.
Other red flags that warrant urgent evaluation include back pain with fever, sudden back pain with spinal tenderness in someone with a history of cancer or osteoporosis, severe or worsening neurological symptoms like progressive leg weakness, and back pain following significant trauma like a fall or car accident. These scenarios are uncommon, but recognizing them matters because early treatment can prevent permanent damage.