Low Back Pain — Red Flags, Symptoms, and Causes

Joseph R. Anticaglia, MD
Medical Advisory board

Years ago, a colleague of mine was removing leaves from a rain gutter, slipped off the ladder, fell, and landed on his back. He was rushed to the hospital complaining of excruciating lower back pain. The ED physician took his medical history, and noted the physical examination was normal except for hypersensitivity in the lumbar- sacral region (lower back).

He was wheeled on a stretcher to the radiology department, and image studies taken of the lower back depicted non-displaced fractures of the spine at levels L3 and L4.

Spinal column NIH National Cancer Institute

The ED doctor ordered an orthopedic surgical consultation. The surgeon reviewed the films and said, “The good news is that no surgery is needed. But it’s going to take several weeks for the fractures to heal. I’m going to prescribe medication to ease the pain. The pain will gradually subside, and don’t think about returning to the office. Make an appointment to see me in about a week, and we’ll take it from there. Any problems, call.” He was handed an instruction sheet of do’s and don’ts.


Lumbar Spine

The five bones in the lower back, labelled L1 to L5, make up the lumbar spine. These 5 bones, also known as vertebra, protect the spinal cord, and are larger compared to the thoracic bones above. Many ligaments, muscles, and tendons support and attach to the 5 vertebra making it possible for you to cross your legs, stand, sit, walk, run, and turn your body in all directions.

Intervertebral Discs

Between each vertebra of the spinal column is a gelatinous substance shaped in the form of a disc. It acts like a “shock absorber” cushioning blows to it, for example, when you run or jump. Pain in the lower back, or pain that radiates down the buttocks, and back of your legs can be due to a herniated or degenerated disc. Discs wear down with age, and getting older puts you at greater risk of developing low back pain

Spinal cord

The spinal cord is nerve tissue that takes off from the base of the skull and rums inferiorly through the spinal canal to approximately the L1 vertebra. Below L1, it continues as a collection of spinal nerves called the cauda equina because it resembles a horse’s tail. The spinal cord relays messages between the brain and your muscles.

Low back pain is an extremely common cause of primary care visits; and it’s the most common cause of disability in patients under the age of forty five. Approximately 80% of low back pain resolves within two weeks, and nine out of ten times within six weeks. The cause of back pain is not often as straight forward as in the case of falling off a ladder. And there are low back pain red flags that can be worrisome to patients and doctors (see below).


Back pain varies from person to person. It may be a dull, achy sensation, or a sharp, jabbing pain. It may be acute, lasting less than six weeks or chronic, lasting more than three months. It can be localized to the lower back, or radiate down your buttocks, or down the back of your legs. Certain positions, or movements like getting up from a chair, bending over, or twisting can exacerbate, make the pain worse.

Back muscle spasms can “come out of the blue,” and cause people to scream in pain. You may walk with a stiff gait, bent over or leaning to one side, or have difficulty standing straight without pain.

Risk Factors

Overweight/obese people with weakened abdominal muscles, adults over the age of 60, sedentary people who exercise little, or not at all are risk factor. In addition, occupational hazards of construction workers or other jobs that necessitate heavy lifting, medical conditions, such as prostate cancer, osteoarthritis, renal stones put you at greater risk for low back pain.

Causes (Etiology) of low back pain include:

  • Back strains and sprains are the most common cause of back pain. A strain is an injury to muscles, or tendons. A sprain is an injury to ligaments. Muscle and ligament injuries can happen when you lift something too heavy, or bend, twist the wrong way.
  • Bulging or Ruptured (Intervertebral) Discs: Between each vertebra, the bones of the spinal column, are soft, gelatinous discs providing protection to the spine. Sometimes the disc bulges, or ruptures outside its normal position in the spinal column to press on nerves causing back pain.
  • Fractures: The bones of the spine can break after falling and landing on your back, or from a car accident resulting in severe back pain. Osteoporosis takes place when bones become porous and brittle, and it places you at an increased risk for fractures, even after minor trauma.
  • Spinal stenosis happens when the spaces in the spine become narrow causing pressure on the spinal cord, and spinal nerves that could result in back pain. Osteoarthritis, degeneration of cartilage and bone, can lead to spinal stenosis.
  • Disease Breast, lung, and prostate cancers can spread to the spine causing low back pain. Infections involving the spinal nerves, such as an epidural abscess, and other conditions like abdominal aortic aneurysm, or kidney stones can result in back pain.
  • Ankylosing spondylitis is an inflammatory arthritis of the spine causing some of the bones in the spine to fuse that can lead to a hunched posture, and low back pain.

Red Flags

Ordinarily, low back pain improves within two to six weeks with rest, moderate exercise, and pain medication. Back pain that doesn’t get better after a few weeks of treatment is a red flag for a possible, underlying, serious problem. What follows are low back pain red flags:

  • Pain doesn’t ease up, or gets worse after 3 to 4 weeks, regardless of treatment
  • Intense pain, or muscle spasms
  • Pain caused by an injury
  • Night pain, or pain at rest
  • If you have back pain along with:
    • Trouble urinating, or bowel problems,
    • Fever,
    • Unexplained weight loss,
    • Stomach pain, or other unexpected symptoms call your doctor.
  • Weakness, numbness, or pain that goes down your buttocks, or legs
  • Cauda Equina Syndrome is a surgical emergency. See glossary

Eight out of ten people experience low back pain at some point in their life. The majority of patients will improve within a few days, and be pain free in four weeks with conservative management. The clinical challenge is to identify red flag patients, make an accurate diagnosis, and initiate the proper treatment plan. A future article will discuss low back pain diagnosis, and treatment.


  1. Arnold Wong et al; Low Back Pain in Older Adults; Scoliosis Spinal Disorders; April 18, 2017
  2. Vincent E. Casiano, et al; Back Pain; StatPearls, 2023
  3. NIH; Back Pain; March 8, 2023
  4. Daniel K. Park, MD, FAAOS; Cauda Equina Syndrome; OrthoInfo, August 2020


Cauda Equina Syndrome happens when the bundle of nerve roots in the lower end of the lumbar spinal cord, known as the cauda equina become compressed cutting off sensation, and movement especially to the nerve roots that control the function of the bladder and bowel. It’s a surgical emergency performed to prevent permanent impairment of the bladder, bowel, loss of sexual sensation, and other complications.

Scoliosis is an abnormal lateral curvature of the spine.

Lordosis excessive inward curvature of the spine.

The sciatic nerve runs down the back of your leg, ending in your foot. It consists of the L4 and L5 nerves plus other sacral nerves. Sciatica occurs when there is pressure on, or damage to the sciatic nerve causing pain, numbness or tingling in the back of the leg. Most often the pain is on one side, It’s often secondary to problems with the intervertebral discs, such as a herniated disc.

Muscles — tissue that supports the spine, and helps you move

Tendons — tissue that connects muscle to bone.

Ligaments — tissue that hold the vertebrae in place that can contract and produce movement.

This article is intended solely as a learning experience. Please consult your physician for diagnostic and treatment options.