Spine pain almost always comes from one of a handful of sources: strained muscles, damaged discs, worn-out joints, narrowed nerve passages, or less commonly, inflammation or infection. Up to 70% of people will experience low back pain at some point in their lives, and about 5% to 10% of those cases become chronic, meaning pain that lasts beyond 12 weeks. Understanding what’s actually generating your pain helps you know what to expect and when to take it seriously.
Muscle and Tendon Strains
The most common reason your spine hurts is also the least complicated. A strain happens when the muscles or tendons supporting your spine get twisted, pulled, or torn. This can come from a single awkward lift, a sudden twist, or simply overstressing your back muscles during activity. The pain is usually localized, meaning it stays in one area rather than traveling down your legs, and it often feels worse with certain movements.
The good news is that most people with a lumbar strain recover fully within about two weeks with basic treatment like rest, gentle movement, and over-the-counter pain relief. These injuries rarely need imaging or advanced care. If your pain started after a specific physical event and stays in your back without spreading, a muscle strain is the most likely explanation.
Disc Problems
Your spine’s vertebrae are separated by rubbery discs that act as shock absorbers. Each disc has a tough outer shell and a soft, gel-like center. A herniated disc occurs when that soft center pushes through a tear in the outer shell, and the bulging material presses on a nearby nerve root. Most herniations happen toward the back and slightly to the side of the disc, where the outer shell is structurally weakest.
The pain from a herniated disc is different from a muscle strain. It’s often described as sharp or burning, and it tends to radiate along the path of whatever nerve is being compressed. In the lower back, this commonly means pain shooting down one leg, sometimes accompanied by numbness, tingling, or weakness. The nerve irritation isn’t purely mechanical, either. The herniated material triggers a chemical inflammatory response that further irritates the nerve roots, which is why even small herniations can produce significant pain.
Not every herniated disc causes symptoms. Some people have disc bulges on imaging and feel nothing at all. Pain depends on whether the displaced material is actually pressing on or chemically irritating a nerve.
Joint Degeneration and Bone Spurs
Each vertebra connects to the ones above and below it through small joints called facet joints. Over time, the cartilage in these joints wears down, just like it does in a knee or hip. This degeneration, sometimes called spinal arthritis, leads to cartilage erosion and inflammation that can make your back stiff and painful, particularly with movement.
As the joints break down, your body sometimes responds by growing extra bone around them. These bone spurs can narrow the spaces where nerves exit the spine, producing radiating pain that mimics sciatica. Facet joint pain tends to be worse with standing, bending backward, or twisting, and it develops gradually rather than appearing after a single injury. It’s one of the most common causes of spine pain in adults over 50.
Spinal Stenosis
Spinal stenosis is a narrowing of the canal that houses your spinal cord and nerve roots. It develops slowly, usually from a combination of thickened ligaments, bone spurs, and bulging discs that collectively shrink the available space. The hallmark symptom is leg pain and heaviness that gets worse with walking or standing upright and improves when you sit down or lean forward.
This pattern exists because your spinal canal naturally gets a bit smaller when you stand straight and opens up when you flex forward. Standing compresses the nerves; bending forward at the waist relieves that compression. Many people with stenosis notice they can walk comfortably while leaning on a shopping cart but struggle to walk the same distance standing upright. Symptoms are typically felt in both legs, though one side may be worse than the other, and they usually involve the entire leg rather than just the thigh or calf.
People with mild stenosis are often completely comfortable at rest. Symptoms only surface when physical activity increases the oxygen demand of the compressed nerve roots beyond what the restricted blood flow can deliver.
Vertebral Slippage
Sometimes one vertebra slides forward over the one below it, a condition called spondylolisthesis. This slippage is graded on a scale of I to V based on how far the bone has moved. Grades I and II (up to 50% slippage) are considered low-grade and often cause mild or no symptoms. Grades III through V represent more significant displacement, with Grade V being a complete slip where the vertebra has moved entirely off the one below it.
One important thing to know: the degree of slippage doesn’t reliably predict how much pain you’ll have. Some people with significant slippage feel fine, while others with minimal displacement have considerable discomfort. Low-grade cases that aren’t progressing are typically managed without surgery. If symptoms don’t improve after about six months of conservative care, or if the slip is high-grade or getting worse, surgery may be considered.
Inflammatory Spinal Conditions
Most spine pain is “mechanical,” meaning it comes from physical stress on structures like muscles, discs, or joints. But some spine pain is driven by your immune system. Ankylosing spondylitis is the best-known example. It causes chronic inflammation where ligaments and tendons attach to the vertebrae, leading to stiffness and pain that tends to be worst in the morning or after long periods of inactivity and improves with movement.
This is the opposite pattern of mechanical pain, which usually feels better with rest and worse with activity. If your back pain wakes you up at night, came on gradually before age 40, and eases once you start moving around, inflammatory disease is worth investigating. Blood tests can check for markers of inflammation and a specific gene (HLA-B27) that’s associated with the condition, though neither test alone confirms a diagnosis.
Spinal Infections
Infections in the vertebrae are uncommon but serious. Back pain is the most common presenting symptom, and notably, fever is often absent, which can delay diagnosis. About one-third of patients develop neurological problems like weakness, sensory loss, or radiating pain. Risk factors include diabetes, a weakened immune system, IV drug use, long-term steroid use, malnutrition, and advanced age. Spinal infections require prompt medical treatment to prevent permanent nerve damage.
When Imaging Is Needed
If you’re dealing with a new episode of back pain and have no alarming symptoms, imaging like X-rays or MRI scans usually isn’t necessary right away. Clinical guidelines recommend a trial of conservative management for up to six weeks before ordering imaging for uncomplicated back pain. Most episodes resolve on their own in that window.
Imaging becomes appropriate when pain persists beyond six weeks despite treatment, or when red flag symptoms are present from the start. Those red flags include pain after significant trauma, unexplained weight loss, a history of cancer, signs of infection, or progressive neurological symptoms like worsening weakness or changes in bladder or bowel function.
Symptoms That Need Emergency Attention
A rare but critical condition called cauda equina syndrome occurs when the bundle of nerves at the base of the spinal cord gets severely compressed, usually by a large disc herniation. The warning signs are specific: numbness in the groin or inner thighs (sometimes called “saddle numbness”), difficulty urinating or loss of bladder control, bowel incontinence, and severe or worsening weakness in the legs. In the incomplete form, you might notice a weak urine stream, loss of the urge to urinate, or the need to strain. In the complete form, the bladder stops functioning and overflow incontinence develops.
This is a surgical emergency. Delay in treatment can result in permanent nerve damage. If you develop any combination of these symptoms alongside back pain, seek immediate medical care.