Back pain has dozens of possible causes, ranging from a simple muscle pull to conditions affecting the spine, organs, or even mental health. Around 619 million people worldwide dealt with low back pain in 2020, and most people experience it at least once in their lives. The good news: the vast majority of cases resolve on their own within a few weeks.
Muscle Strains and Ligament Sprains
Strains and sprains are the most common causes of back pain. You can injure the muscles, tendons, or ligaments in your back by lifting something too heavy, twisting awkwardly, or even sneezing or coughing at the wrong angle. The pain usually feels like a dull ache or tightness, sometimes with muscle spasms, and it tends to get worse with movement.
Most people with strains and sprains recover within a few days to a few weeks with rest, ice, and basic pain relievers. After a couple of days of rest, gradually returning to normal activity actually helps more than staying in bed. These injuries rarely cause long-term problems.
Disc Problems
Your spinal bones are separated by soft, cushion-like discs that absorb shock. If the soft inner material of a disc leaks out (a herniated disc), it can press directly on nearby nerves. This often causes sharp, shooting pain that travels down one leg, commonly called sciatica. You might also feel numbness or tingling in your leg or foot.
Disc herniations are more common in people between 30 and 50. Lifting with a rounded back, repetitive bending, and prolonged sitting all increase the risk. Many herniated discs improve without surgery over 6 to 12 weeks as the body gradually reabsorbs the leaked material, though larger herniations sometimes need more intervention.
Spinal Stenosis and Bone Spurs
Spinal stenosis happens when the space inside the spinal column narrows, squeezing the spinal cord and nerves. This narrowing usually develops gradually from age-related changes. Wear-and-tear arthritis can cause extra bone growth (bone spurs) that pushes into the spinal canal. The ligaments that hold the spine together can also thicken and stiffen over time, further reducing the available space.
Stenosis typically affects people over 50 and causes pain, numbness, or weakness in the legs that gets worse with standing and walking. A hallmark sign is relief when you lean forward, like over a shopping cart, because that position temporarily opens up the spinal canal.
Inflammatory Conditions
Not all back pain is mechanical. Ankylosing spondylitis is an inflammatory condition that primarily affects the spine and sacroiliac joints (where the spine meets the pelvis). It causes pain and stiffness in the lower back and hips that behaves very differently from a pulled muscle: it’s worst in the morning or after periods of inactivity, improves with exercise, and gets worse with rest. The pain often comes on slowly and may wake you from sleep.
This pattern is the key distinguishing feature. Mechanical back pain from strains or disc problems generally feels better with rest and worse with activity. If your back pain consistently improves when you move around and flares when you sit still, that’s worth bringing up with a doctor. Ankylosing spondylitis tends to start in your 20s or 30s and is more common in men, though it occurs in women too.
Workplace and Lifestyle Risk Factors
What you do all day has a direct effect on your back. Research on construction workers found that those who spent two or more hours per shift handling heavy stones had roughly 2.5 times the risk of developing low back pain compared to workers with lighter tasks. The size and weight of materials, combined with the duration of exposure, predicted future back problems more reliably than almost any other factor.
You don’t need to work construction for your job to cause back pain, though. Prolonged sitting, especially with poor posture, puts sustained pressure on the lower spine. Vibration exposure from driving trucks or operating machinery is another well-established risk factor. On the other end of the spectrum, a completely sedentary lifestyle weakens the core muscles that support the spine, making injury more likely when you do exert yourself.
Carrying excess weight, particularly around the midsection, shifts your center of gravity forward and increases the load on your lower back. Smoking also raises the risk, likely because it reduces blood flow to the spinal discs, speeding up their degeneration.
Conditions Specific to Women
Pregnancy is one of the most common causes of back pain in women. As the uterus grows, it shifts your center of gravity and loosens the ligaments in the pelvic area, both of which strain the lower back. This pain typically builds during the second and third trimesters and resolves after delivery.
Endometriosis can also cause lower back pain, particularly around menstruation. The condition involves tissue similar to the uterine lining growing outside the uterus, and it can trigger cramping, lower back pain, and abdominal discomfort that typically worsens before and during periods. Because the back pain follows a cyclical pattern tied to the menstrual cycle, it can sometimes be distinguished from other causes.
How Stress and Beliefs Affect Pain
Your mental state plays a surprisingly large role in whether back pain resolves or becomes chronic. A prospective study tracking patients over three months found that people who expected their pain to persist were significantly more likely to still have it at the three-month mark, even after accounting for how severe the original injury was. Fear of movement, the worry that activity will cause further damage, also predicted the transition from short-term pain to a long-term problem.
This doesn’t mean the pain is imaginary. Pain is processed in the brain, and stress, anxiety, and catastrophic thinking can amplify pain signals and keep muscles tense. The practical takeaway is that staying active within your limits, rather than avoiding all movement out of fear, genuinely reduces your risk of developing chronic back pain.
When Imaging Is Actually Needed
If you’re wondering whether you need an X-ray or MRI, the answer for most new back pain is no. The American College of Radiology considers uncomplicated back pain, even with leg symptoms, a self-limiting condition that doesn’t warrant imaging. Most cases respond to conservative management within four to six weeks.
Imaging becomes appropriate if your pain hasn’t improved after six weeks of basic treatment, or if you have any warning signs that suggest something more serious. These red flags include:
- Unexplained weight loss or a history of cancer
- Pain following significant trauma, or a minor fall in an older adult
- Fever, recent urinary infection, or intravenous drug use
- Progressive weakness in one or both legs
- New bladder or bowel problems, like difficulty urinating or incontinence
- Numbness in the groin, buttocks, or inner thighs (called saddle anesthesia)
That last cluster of symptoms, loss of bladder or bowel control combined with saddle numbness and leg weakness, can indicate cauda equina syndrome, a rare condition where the bundle of nerves at the base of the spine is severely compressed. This is a surgical emergency. Urinary retention, where your bladder fills but you don’t feel the urge to go, is the most common early symptom. If you experience any combination of these, seek immediate medical attention.
Less Obvious Causes
Several conditions outside the spine can produce back pain. Kidney stones and kidney infections cause pain in the flank area, usually on one side, that can be mistaken for a muscle problem. The difference is that kidney-related pain often comes with urinary symptoms like burning, frequency, or blood in the urine.
Abdominal aortic aneurysms, where the large blood vessel in the abdomen balloons outward, can cause a deep, steady pain in the lower back. Pancreatitis and gallbladder problems sometimes refer pain to the mid-back. These causes are less common but worth considering if your back pain doesn’t follow the typical pattern of getting worse with movement or better with rest, or if it comes with symptoms that seem unrelated to your back.