Why Does My Lower Back Hurt?

Medically Reviewed by Jabeen Begum, MD on February 16, 2023
5 min read

Your lower back, which spans from the bottom of your rib cage to the top of your legs, is a hardworking thing. It supports the weight of your upper body. About 80% of people have low back pain sometime in their lives.

That area of your body has a lot of moving parts that can cause trouble:

  • Vertebrae. These five bones are numbered L1 through L5 (“L” stands for “lumbar”).
  • Disks. These spongy structures between the vertebrae cushion the bones as your body moves.
  • Ligaments connect the vertebrae and keep them in place.
  • Tendons connect your muscles to your spinal column.
  • Nerves. Among them is the sciatic nerve, the longest in your body.

Lifestyle Causes

Your back is at the mercy of bad habits like:

  • Slouching at your desk
  • Lifting and pulling heavy objects with your back rather your legs
  • Being overweight
  • Not exercising enough
  • Smoking
  • Wearing high heels
  • Carrying an overloaded backpack

All of these things can lead to lower back pain.

Injury Causes

Falling down, getting into a car accident, or even overdoing it in that pick-up game over the weekend can cause problems you feel in your lower back, like:

  • Spine/vertebral fractures: Your back may have a broken bone if it gets hit hard or you fall from a great height.

  • Sprains and strains: This means you overstretch or tear your tendons or muscle. You can do this by twisting, lifting something that’s too heavy, or lifting something the wrong way.

  • Spasms: These are muscle contractions, and they hurt. They generally happen when you sprain or strain your lower back.

Mechanical Problems

  • Herniated or ruptured disks. Normal disks are rubbery. When they become squeezed, a portion bulges out between your vertebrae.
  • Radiculopathy. A spinal nerve can become pinched or inflamed. This can cause low back pain to travel (radiate) down your legs. It can also cause numbness or tingling.
  • Sciatica. This is the type of radiculopathy that affects the sciatic nerve, which runs from your butt down the backs of your legs. When it’s inflamed, you may have burning or pain that can feel like an electrical shock and can go all the way down to your feet.
  • Spondylolisthesis. In this condition, a vertebra slips out of place and pinches spinal nerves.
  • Spinal stenosis. Your spinal column may narrow over time, putting pressure on your nerves. Your legs may feel numb and grow weaker.
  • Scoliosis . Your spine can be curved, which causes severe back pain.
  • Bulging disks. The stuff inside your disks “bulges,” but not as much as with a herniated disk. They often cause no symptoms on their own, but they can bring pain if the disk pushes up against a nerve root.
  • Degenerative disk disease. The disks that separate your vertebrae wear down. This sometimes causes the bones to rub together. Age is usually the reason, but sports and injuries can be culprits, too.
  • Inflammation and movement problems of the sacroiliac joint. This joint sits at the bottom of the spine, on either side of the pelvis. It transfers the weight of your upper body to your lower body. This can start to bother you after you’ve been injured, if you have an infection, if you have arthritis, or if you’re pregnant. Abnormal movement, such as too much movement of the joint, can also cause long-term pain.
  • Cauda equina syndrome. This happens if a ruptured disk pushes down into the nerve roots in your spine. It may be what’s causing your pain if bladder and bowel control have been an issue for you lately.
  • Arthritis. This causes stiffness, swelling, and inflammation in your joints. If your doctor mentions “ankylosing spondylitis,” they're talking about a type of inflammatory arthritis that affects the joints and ligaments along your spine.
  • Osteoarthritis. This is when your cartilage and bone begin to break down and there is inflammation.
  • Psoriatic arthritis (PsA). This can affect many parts of the body. About half of people with PsA also have back pain. You may hear it called spondylitis or axial arthritis. It often shows up after you’ve had PsA for a while. Some people can have back pain for years before they find out they have PsA.
  • Non-radiographic axial spondyloarthritis (nr-AxSpA). This is an early form of AS. You have the same painful symptoms, but damage to your SI joints doesn’t show up on X-rays. That’s what non-radiographic means. Not everyone with nr-AxSpA goes on to have full AS. There’s no way to know who will get it and who won’t.

Other Health Condition Causes

Back pain can also be a sign of a serious condition that needs attention right away. For example:

  • Infections of your vertebrae (osteomyelitis), disks (discitis), or the joints that connect your spine to your pelvis (sacroiliitis)
  • Abdominal aortic aneurysm (when the blood vessel that supplies your belly, pelvis, and legs becomes swollen)
  • Kidney stones (pain in the lower back, usually just on one side)
  • Tumors (though this is rare)
  • Pregnancy. Your pelvis is changing, and so is the way you carry weight. Back problems usually go away once your baby arrives.
  • Fibromyalgia, a condition that causes widespread muscle pain

If your back pain is short-term – meaning it lasts a few days or a few weeks – doctors call it “acute.” If it has gone on for 3 months or more, it’s considered chronic.

You may hear the term “mechanical” low back pain. That means the problem involves the moving parts of your back – disks, vertebrae, ligaments, tendons, and muscles.

Other names for low back pain include lumbar syndrome and lumbago.

How your back pain feels can vary. You might describe yours as:

  • Aching
  • Burning
  • Sharp
  • Stabbing
  • Dull
  • Vague

It may also radiate down into your butt, hips, or thighs.

Certain things make it more likely that you will have low back pain:

  • Age. Most people first have trouble with their backs between ages 30 and 50, and the problem gets worse as they get older. That’s mostly because of wear and tear.
  • Being out of shape. If the muscles in your belly and back are weak, they don’t do as good a job of supporting the structure of your spine. You’re also more likely to hurt your back if you suddenly ramp up your exercising after you’ve been inactive.
  • Obesity. Extra weight puts a strain on back muscles.
  • Genetics. Some causes, like inflammatory diseases, are inherited from one of your parents.
  • Your job. If you have to lift, push, pull, and twist at work, you may be at risk for more back pain. But desk jobs come with their own set of problems. If you sit at a computer all day, you may have back pain, especially if you have poor posture.
  • A heavy backpack. Put your child’s school backpack on the scale. If it weighs more than 20% of their weight, it’s too heavy and could cause muscle strain and back pain.

Most back pain gets better after a few weeks. But you should call the doctor if:

  • Your pain is constant or intense, especially at night or when you lie down.
  • Your pain spreads down one or both legs.
  • You feel numbness or tingling in one or both legs.
  • You’re losing weight without trying.

Go to the emergency room right away if you have any of these symptoms: