The most common reason your lower back hurts is a strain or sprain of the muscles, tendons, or ligaments surrounding your spine. These soft-tissue injuries account for the majority of low back pain episodes, and most improve within four to six weeks with basic self-care. But several other causes, from disc problems to referred pain from internal organs, can produce similar symptoms. Understanding what’s behind your pain helps you respond appropriately.
Muscle Strains and Ligament Sprains
Lifting something too heavy, lifting with poor form, or even a sudden twist or awkward bend can overstretch or tear the muscles and ligaments in your lower back. Some people strain their back doing something as minor as sneezing or coughing. The resulting pain is usually dull and achy, worsens with certain movements, and improves when you change positions or lie down. You might also notice stiffness or muscle spasms around the injury site.
These injuries heal on their own in most cases. The pain tends to peak in the first few days, then gradually ease over the following weeks. If you’ve been sitting for long hours, sleeping in an awkward position, or recently increased your physical activity, a simple strain is the most likely explanation.
Disc Problems
Between each vertebra in your spine sits a rubbery disc that acts as a cushion. Over time, or after an injury, these discs can develop problems that cause lower back pain.
A bulging disc happens when the outer layer of the disc pushes outward, a bit like a hamburger patty that’s too wide for its bun. Usually at least a quarter to half of the disc’s outer edge is affected, but the inner material stays contained. Bulging discs don’t always cause pain.
A herniated disc is different. A crack forms in that tough outer layer, and some of the softer inner material pokes through. This is more likely to cause pain because the protruding material can press against or inflame nearby nerve roots. When a herniated disc in the lower back irritates the sciatic nerve, which runs from the lower spine through the buttocks and down each leg, you may feel shooting pain, tingling, or numbness radiating into one leg. This pattern is called sciatica.
Degenerative Changes (That May Not Matter)
Here’s something that surprises most people: wear-and-tear changes in the spine are extremely common and often painless. A large review of imaging studies in over 3,000 people with no back pain at all found that 52% of 30-year-olds already showed disc degeneration on MRI. By age 50, that number hit 80%. By 80, it was 96%. Disc bulges appeared in 50% of pain-free 40-year-olds.
This means that if you get an MRI and it shows degenerative changes, those findings may have nothing to do with your current pain. It’s one reason doctors typically don’t recommend imaging for uncomplicated low back pain. More than half of adults in their 30s already have degenerative findings that are completely incidental. An MRI can actually make things worse by leading to unnecessary worry, additional procedures, or treatments that target something that wasn’t causing your symptoms in the first place.
When Imaging Is Appropriate
Current guidelines from the American College of Radiology are clear: imaging is not appropriate for the initial workup of low back pain when there are no red flags and no prior treatment has been tried. Multiple studies have confirmed that routine imaging provides no clinical benefit for straightforward cases and can lead to increased, unnecessary healthcare use.
Imaging becomes appropriate after about six weeks of treatment that hasn’t improved your symptoms, or immediately if you have warning signs of something serious (more on those below). If you’ve had prior spinal surgery and develop new or worsening symptoms, imaging is also reasonable from the start.
Could It Be Something Else Entirely?
Pain in the lower back doesn’t always originate from the spine. Kidney stones, for instance, can produce intense pain in the lower back or flank area. A few differences help distinguish the two:
- Location: Kidney stone pain tends to focus on one side, underneath the ribs, rather than across the center of the lower back.
- Response to movement: Muscular back pain often shifts or briefly eases when you change positions. Kidney stone pain stays constant regardless of how you move.
- Pain pattern: Kidney stone pain typically comes in waves that change in intensity, while muscular back pain is more steady.
- Onset: Kidney stone pain usually strikes suddenly and severely, without any obvious physical trigger.
- Progression: Kidney stone pain often starts near the kidney and migrates downward toward the abdomen and groin as the stone moves through the urinary tract.
Other internal causes of referred lower back pain include urinary tract infections, endometriosis, and abdominal aortic problems, though these are far less common than musculoskeletal causes.
What to Do Right Now
One of the most persistent myths about back pain is that you need prolonged bed rest. The opposite is true. Staying as active as possible is one of the most effective things you can do. It’s fine to reduce your normal activity for the first day or two to let the initial inflammation settle, but after that, gentle movement helps more than lying still.
For pain relief, anti-inflammatory medications like ibuprofen or naproxen tend to work better than acetaminophen for back pain because they reduce both pain and inflammation. Acetaminophen is gentler on the stomach but doesn’t address inflammation, which is often part of the problem. Applying ice for the first 48 to 72 hours and then switching to heat can also help.
Walking, gentle stretching, and gradually returning to your normal routine are more effective recovery strategies than waiting for the pain to fully resolve before moving. Most people see significant improvement within four to six weeks.
Warning Signs That Need Immediate Attention
Rarely, lower back pain signals a serious condition called cauda equina syndrome, where the bundle of nerves at the base of the spinal cord becomes severely compressed. This is a medical emergency. The symptoms to watch for are specific and distinct from ordinary back pain:
- Bladder changes: Difficulty urinating, not feeling the urge to urinate when your bladder is full, or loss of bladder control.
- Bowel incontinence: Loss of control over bowel function.
- Saddle numbness: Loss of sensation in the area that would contact a saddle, including the inner thighs, buttocks, and groin.
- Progressive leg weakness: Weakness in one or both legs that is getting worse, not just pain.
- Sexual dysfunction: Sudden onset of new symptoms.
If you experience any combination of these alongside your back pain, get to an emergency room. Cauda equina syndrome requires urgent treatment to prevent permanent nerve damage. Back pain accompanied by unexplained fever, significant weight loss, or a history of cancer also warrants prompt evaluation.