Lower back pain is the single leading cause of disability worldwide, affecting an estimated 619 million people in 2020 alone. Most people experience it at least once in their lives. The cause is almost always one of a handful of common problems, and figuring out which one applies to you comes down to where the pain is, what makes it better or worse, and how long it’s been going on.
Muscle Strains and Sprains
Strains and sprains are the most common cause of lower back pain. You can injure the muscles, tendons, or ligaments in your lower back by lifting something heavy, lifting with poor form, twisting awkwardly, or even just sneezing or coughing at the wrong angle. The pain tends to be localized to the lower back itself, often feels achy or stiff, and usually gets worse with certain movements.
The good news is that most strains and sprains heal on their own within a few days to a few weeks. Rest, ice, and over-the-counter pain relievers are typically enough. After a few days, gradually returning to normal activity actually helps recovery more than staying in bed. Most people with these injuries recover fully without long-term issues.
Disc Problems
Between each vertebra in your spine sits a soft, rubbery disc that acts as a shock absorber. Sometimes the outer layer of a disc tears, and the softer material inside pushes out and presses on a nearby nerve. This is a herniated disc, and it produces a very different kind of pain than a simple strain.
The hallmark of a herniated disc in the lower back is pain that doesn’t stay in the back. You’ll typically feel sharp or burning pain that travels into your buttock, thigh, calf, or even your foot. The pain often shoots down your leg when you cough, sneeze, or shift into certain positions. You may also notice numbness, tingling, or weakness in the affected leg. If you’re only feeling a dull ache in the center of your lower back with no leg symptoms, a disc herniation is less likely.
Here’s something worth knowing: many people have disc bulges on imaging that cause no symptoms at all. A bulging disc on an MRI doesn’t automatically explain your pain, which is one reason doctors don’t rush to order imaging for most cases of back pain.
Sciatica
Sciatica is not a diagnosis on its own. It’s a description of pain that follows the path of the sciatic nerve, which starts near the base of your spine, passes through your pelvis and buttock, then runs down the back of each thigh into your lower leg. A herniated disc is one of the most common causes, but anything that compresses or irritates this nerve can produce sciatica.
The pattern is distinctive: pain, tingling, or numbness that radiates from your lower back or buttock down the back of your leg. You may feel symptoms all the way into your feet or toes. Sometimes the leg pain is actually worse than the back pain. During an exam, a doctor will often perform a straight leg raise test, slowly lifting one leg while you lie flat, to see when symptoms appear. Changes in how you walk and weakness in specific muscle groups also help identify which nerve is involved.
Spinal Stenosis
If your back pain started gradually after age 50, spinal stenosis is a common culprit. This happens when the spinal canal narrows over time, squeezing the nerves inside it. The most common cause is simple wear-and-tear arthritis. As the spine ages, bone spurs can grow and push into the canal, ligaments can thicken and stiffen, and disc herniations become more likely. All of these shrink the available space for your spinal cord and nerves.
Spinal stenosis in the lower back produces a characteristic pattern: pain or cramping in one or both legs when you stand for a long time or walk. The symptoms get better when you bend forward or sit down. Many people notice they can walk farther if they lean on a shopping cart, because bending forward opens up space in the spinal canal. Symptoms often start slowly and worsen over time, and many people with narrowing on imaging have no symptoms at all.
Spondylolisthesis
Spondylolisthesis occurs when one vertebra slips forward over the one below it. Doctors grade the slippage on a scale from Grade I (mild) to Grade IV (severe). Grades I and II are the most common, and many people live with low-grade slippage without severe symptoms or the need for surgery.
High-grade slippage (Grades III and IV) is much more likely to cause significant pain and may require surgery, especially if the slippage affects your ability to stand, walk, or move normally. The pain from spondylolisthesis tends to worsen with activity and may produce symptoms similar to spinal stenosis if the slipped vertebra compresses nearby nerves.
Inflammatory Back Pain
Not all back pain is mechanical. A smaller but important category is inflammatory back pain, caused by conditions where the immune system attacks the joints of the spine. The most well-known of these is ankylosing spondylitis. Inflammatory back pain behaves very differently from a strain or disc problem, and recognizing the pattern can save you years of misdiagnosis.
Inflammatory back pain has five key features that set it apart:
- Age of onset: It usually begins before age 35, with a gradual, creeping start rather than a sudden injury.
- Duration: The pain has been present for more than three months.
- Worse with rest: Pain and stiffness get worse with immobility, especially at night and first thing in the morning.
- Better with movement: Unlike mechanical pain, exercise and physical activity tend to ease the symptoms rather than aggravate them.
- Responds well to anti-inflammatory medication: Over-the-counter anti-inflammatories like ibuprofen provide significant relief for most people with this type of pain.
If you’re waking up with a stiff, painful back that loosens up after you start moving, and this has been going on for months, bring this pattern to your doctor’s attention specifically.
Lifestyle Factors That Contribute
Your daily habits play a measurable role in lower back pain risk. A large meta-analysis found that a sedentary lifestyle increases the odds of developing lower back pain by about 24%. Prolonged sitting raises the risk by 42%, and long driving times roughly double it. Being overweight increases risk by 35%, and smoking by 28%.
These aren’t just correlations in the background. If you sit at a desk all day, drive long distances, carry extra weight, or smoke, these factors may be directly contributing to your pain or slowing your recovery. Addressing even one of them can make a meaningful difference, particularly for pain that keeps coming back.
Symptoms That Need Immediate Attention
The vast majority of lower back pain is not dangerous. But a small number of cases involve serious underlying problems that require urgent evaluation. You should seek immediate medical care if your back pain is accompanied by any of the following:
- Loss of bowel or bladder control: This can signal a condition called cauda equina syndrome, where nerves at the base of the spine are severely compressed. This is a surgical emergency.
- Numbness in the groin or inner thighs (saddle area): Another sign of cauda equina syndrome.
- Progressive weakness in both legs: Especially if it’s getting worse over hours or days.
- Fever combined with back pain: This may indicate a spinal infection, particularly in people with diabetes, weakened immune systems, or recent spinal procedures.
- Unexplained weight loss or night sweats: These raise concern for malignancy as an underlying cause.
- Back pain after significant trauma: A fall, car accident, or other injury, especially in older adults, warrants evaluation for fracture.
How to Narrow Down Your Cause
You can start sorting out what’s behind your pain by asking yourself a few questions. Is the pain only in your back, or does it travel into your leg? Pain that stays in the lower back points toward a strain, sprain, or general wear and tear. Pain that radiates down a leg suggests nerve involvement from a disc herniation or stenosis.
Next, think about what makes it better or worse. Pain that improves with rest is more likely mechanical. Pain that improves with movement and worsens overnight points toward an inflammatory cause. Pain in the legs that eases when you sit or lean forward is a classic pattern for spinal stenosis.
Finally, consider timing. Pain that started suddenly after lifting or twisting is likely a strain. Pain that crept in gradually over weeks or months, especially in someone over 50, may reflect degenerative changes. And pain that’s persisted for more than three months in someone under 35, particularly with morning stiffness, deserves a closer look for inflammatory disease.
Most lower back pain resolves within a few weeks regardless of cause. When it doesn’t, or when it comes with the red-flag symptoms above, imaging and a thorough exam can help pin down the specific problem and guide the right treatment.