Back pain is one of the most common medical complaints in America today.

In fact, according to the National Institute of Neurological Disorders and Stroke, roughly 80 percent of adults experience low back pain at some point in their lifetimes.

The cause of back pain is all too often left undiagnosed. It’s discounted as an annoying problem, hidden by over-the-counter pain medications and frequently left untreated.

However, a specific diagnosis of the cause is possible. In some cases, back pain may be the result of ankylosing spondylitis (AS).

AS is a progressive, inflammatory form of arthritis affecting the axial skeleton (spine) and nearby joints.

The chronic inflammation over time can cause the vertebrae in the spine to fuse together. As a result, the spine will be less flexible.

As the disease progresses, the spine loses its flexibility, and the back pain grows worse. The initial symptoms of the disease include:

  • chronic pain in your lower back and hips
  • stiffness in your lower back and hips
  • increased pain and stiffness in the morning or after long periods of being inactive

Many people with the disease hunch forward. In advanced cases of the disease, the inflammation may be so bad that a person can’t lift their head in order to see in front of them.

Risk factors for AS include:

  • Age: Late adolescence or early adulthood is when onset is likely to occur.
  • Sex: Men are generally more likely to develop AS.
  • Genetics: Most people with AS have the HLA-B27 gene, though it doesn’t guarantee development of the disease.

Stiffness and reduced flexibility

If left untreated, the chronic inflammation can cause the vertebrae in your spine to fuse together. When this happens, your spine may become less flexible and more rigid.

You may have decreased range of motion when:

  • bending
  • twisting
  • turning

You may also have greater and more frequent back pain.

The inflammation is not limited to your spine and vertebrae. It can involve other nearby joints, including your:

  • hips
  • shoulders
  • ribs

This may cause more pain and stiffness in your body.

The inflammation may also affect the tendons and ligaments that connect to your bones, which may make moving joints increasingly difficult.

In some cases, organs, such as your bowel, heart, or even your lungs can be affected by the inflammatory process.


Iritis (or anterior uveitis) is a type of eye inflammation that about 50 percent of people with AS experience. If inflammation spreads to your eyes, you may develop:

  • eye pain
  • sensitivity to light
  • blurred vision

Iritis is typically treated with topical corticosteroid eye drops and needs immediate medical attention to prevent damage.

Joint damage

Although the main area of inflammation is the spine, pain and joint damage may also occur in the:

  • jaw
  • chest
  • neck
  • shoulders
  • hips
  • knees
  • ankles

According to the Spondylitis Association of America, about 15 percent of people with AS have jaw inflammation, which can affect chewing and swallowing.


One study showed about 86 percent of people with AS experience:

  • fatigue, an extreme form of tiredness
  • brain fog
  • a lack of energy

A number of factors can contribute to this, such as:

  • anemia
  • loss of sleep from pain or discomfort
  • muscle weakness forcing your body to work harder
  • depression, other mental health issues, and neurological changes
  • certain drugs used to treat arthritis

Treating fatigue often requires multiple treatments to address the varying contributors.

Osteoporosis and bone fractures

Osteoporosis is a frequent complication for people with AS and can cause weakened bones. Up to half of all people with this condition also have osteoporosis.

Damaged, weakened bones may break more easily. For people with AS, this is especially true in the spine’s vertebrae. Fractures in the bones of your spine may damage your spinal cord and the nerves connected to it.

Cardiovascular disease

AS has been associated with number of cardiovascular diseases, including:

  • aortitis
  • aortic valve disease
  • cardiomyopathy
  • ischemic heart disease

Inflammation can affect your heart and aorta. Over time, the aorta may become enlarged and distorted as a result of the inflammation. A damaged aortic valve may impair your heart’s ability to function properly.

Lung complications may include:

  • fibrosis of the upper lobes
  • interstitial lung disease
  • ventilatory impairment
  • sleep apnea
  • collapsed lungs

GI disorder

Many people with AS experience inflammation of the gastrointestinal tract and bowels causing:

  • stomach pain
  • diarrhea
  • other digestive problems

AS has links to:

Cauda Equina Syndrome

Cauda equina syndrome (CES) is a rare debilitating neurological complication of AS that mostly occurs in people who’ve had AS for many years.

CES can disrupt motor and sensory function to the lower legs and bladder. It can even cause paralysis.

You may experience:

  • low back pain that may radiate down the leg
  • numbness or reduced reflexes in the legs
  • loss of control over bladder or bowels


Amyloidosis occurs when a protein called amyloid builds up in your tissues and organs. Amyloid isn’t naturally found in the body and can cause organ failure.

Renal amyloidosis was the most common form found in people with AS.

Ideally, you and your doctor will discover and diagnose your AS early. You can begin early treatment that can help you reduce the symptoms and lessen the chance possible long-term complications.

However, not everyone will be diagnosed with this condition at an early stage. It’s important to see your doctor if you’re experiencing back pain and are unsure of the cause.

If you suspect your symptoms are related to AS, see your doctor as soon as you can. The longer you wait, the greater the chances are you’ll experience more severe symptoms and complications.