Ankylosing Spondylitis (AS)


What is ankylosing spondylitis (AS)?

Ankylosing spondylitis (pronounced ankle-oh-sing spon-dill-eye-tiss) is a form of arthritis that causes chronic (long-term) spine inflammation. Ankylosing spondylitis (AS) inflames the sacroiliac joints located between the base of the spine and pelvis. This inflammation, called sacroiliitis, is one of the first signs of AS. Inflammation often spreads to joints between the vertebrae, the bones that make up the spinal column. This condition is known as spondylitis.

Some people with AS experience severe, persistent back and hip pain and stiffness. Others have milder symptoms that come and go. Over time, new bone formations may fuse vertebrae sections together, making the spine rigid. This condition is called ankylosis.

How common is ankylosing spondylitis (AS)?

Ankylosing spondylitis belongs to a group of diseases known as spondyloarthropathies. Between three and 13 out of 1,000 Americans have one of these diseases.

Who might have ankylosing spondylitis (AS)?

Anyone can get AS, although it affects more men than women. Symptoms usually appear in people between the ages of 17 and 45. Ankylosing spondylitis has a genetic link and may run in families.

Symptoms and Causes

What causes ankylosing spondylitis (AS)?

About 95% of people who have AS have a variation of the human leukocyte antigen-B gene (HLA-B). This changed, or mutated, gene produces a protein called HLA-B27 that increases disease risk. However, most people with a mutated HLA-B gene don’t get AS. In fact, 80% of children who inherit the mutated gene from a parent with AS don’t develop the disease. More than 60 genes have been linked to the condition.

Having one of these conditions may also increase your risk:

What are the symptoms of ankylosing spondylitis (AS)?

Symptoms typically appear between the ages of 17 and 45 but may develop in younger children or older adults. Some people have persistent pain, while others experience milder symptoms. Symptoms may flare up (worsen) and improve (go into remission) off and on. If you have ankylosing spondylitis, you may experience:

Diagnosis and Tests

How is ankylosing spondylitis (AS) diagnosed?

There isn’t a test that definitively diagnoses ankylosing spondylitis. After reviewing your symptoms and family history, your healthcare provider will perform a physical exam. Your provider may order one or more of these tests to help guide diagnosis:

  • Imaging scans: Magnetic resonance imaging (MRI) scans can detect spine problems earlier than traditional X-rays. Still, your provider may order spine X-rays to check for arthritis or rule out other problems.
  • Blood tests: Blood tests can check for the presence of the HLA-B27 gene. About 8% of people of European descent have this gene, but only a quarter of them develop ankylosing spondylitis.

Management and Treatment

What are the complications of ankylosing spondylitis (AS)?

Ankylosing spondylitis may affect more than the spine. The disease may inflame joints in the pelvis, shoulders, hips and knees, and between the spine and ribs. People with AS are more prone to spinal fractures (broken vertebrae). Other complications include:

  • Fused vertebrae (ankylosis).
  • Kyphosis (forward curvature of the spine).
  • Osteoporosis.
  • Painful eye inflammation (iritis or uveitis) and sensitivity to light (photophobia).
  • Heart disease, including aortitis, arrhythmia and cardiomyopathy.
  • Chest pain that affects breathing.
  • Jaw inflammation.
  • Cauda equina syndrome (nerve scarring and inflammation).

How is ankylosing spondylitis (AS) managed or treated?

Ankylosing spondylitis is a lifelong condition. While there’s no cure, treatments can prevent long-term complications, reduce joint damage and ease pain. Treatments include:

  • Exercise: Regular physical activity can slow or stop disease progression. Many people experience worse pain when they’re inactive. Movement seems to lessen pain. Your healthcare provider can recommend safe exercises.
  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs, including ibuprofen (Advil®) and naproxen (Aleve®), ease pain and inflammation.
  • Disease-modifying anti-rheumatic drugs (DMARDs): Medications such as sulfasalazine reduce pain and joint swelling. The drugs also treat lesions caused by inflammatory bowel disease. Newer DMARDs called biologics help control inflammation by changing the immune system. Biologics include tumor necrosis factor (TNF) and interleukin inhibitors (IL-17).
  • Corticosteroids: Injectable corticosteroids temporarily ease joint pain and inflammation.
  • Surgery: A small number of people with ankylosing spondylitis may need surgery. Joint replacement surgery implants an artificial joint. Kyphoplasty corrects a curved spine.

What other steps can I take to manage or treat ankylosing spondylitis (AS)?

In addition to standard AS treatments, these steps may also help ease inflammation and pain:

  • Eat a nutritious diet: Fried foods, processed meats and foods high in fat and sugar can have an inflammatory effect. Anti-inflammatory diets, such as the Mediterranean diet, may help fight inflammation.
  • Maintain a healthy weight: Obesity and excess weight puts pressure on joints and bones.
  • Limit alcohol consumption: Drinking too much alcohol can weaken bones and increase the risk of osteoporosis.
  • Stop smoking: Tobacco use accelerates spinal damage and intensifies pain. Your provider can help you quit smoking.


How can I prevent ankylosing spondylitis (AS)?

Because ankylosing spondylitis has no known cause, there isn’t any way to prevent it.

Outlook / Prognosis

What is the prognosis (outlook) for people who have ankylosing spondylitis (AS)?

Ankylosing spondylitis symptoms may gradually worsen as you age. The condition is rarely disabling or life-threatening. Still, symptoms like joint pain may interfere with your ability to do the things you love. Early interventions can ease inflammation and pain. A combination of physical activity and medications can help.

Living With

When should I call the doctor?

You should call your healthcare provider if you have AS and experience:

  • Chest pain.
  • Difficulty breathing.
  • Vision problems.
  • Severe back pain or other joint pain.
  • Spine rigidity.
  • Unexplained weight loss.

What questions should I ask my doctor?

If you have ankylosing spondylitis, you may want to ask your healthcare provider:

  • Why did I get ankylosing spondylitis?
  • What is the best treatment for ankylosing spondylitis?
  • What are the treatment risks and side effects?
  • What lifestyle changes should I make to manage the condition?
  • Is my family at risk for developing ankylosing spondylitis? If so, should we get genetic tests?
  • Am I at risk for other types of arthritis or back problems?
  • What type of ongoing care do I need?
  • Should I look out for signs of complications?

A note from Cleveland Clinic

Ankylosing spondylitis is a form of arthritis that mostly affects the spine. It’s a lifelong condition without a cure. However, exercise, medications and lifestyle changes can help manage symptoms so you can enjoy a long, productive life. It’s rare for someone with AS to become severely disabled. Talk to your healthcare provider about the steps you can take to stay active and manage symptoms.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 07/21/2020.

Learn more about our editorial process.


  • Arthritis Foundation. Axial Spondylarthritis. ( Accessed 7/22/2020.
  • National Institute of Arthritis and Musculoskeletal and Skin Diseases. Ankylosing Spondylitis. ( Accessed 7/22/2020.
  • Spondylitis Association of America. Overview of Ankylosing Spondylitis. ( Accessed 7/22/2020.
  • U.S. National Library of Medicine. Ankylosing Spondylitis. ( Accessed 7/22/2020.

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