Ankylosing Spondylitis (AS)

What Is Ankylosing Spondylitis?


Ankylosing spondylitis (AS) is a rare type of arthritis that causes pain and stiffness in your spine. This lifelong condition usually starts in your lower back. But it also can spread up to your neck or damage joints in other parts of your body.

"Ankylosis" means fused bones or other hard tissue. "Spondylitis" means inflammation in your spinal bones, or vertebrae. Severe cases can leave your spine hunched. AS isn’t curable. But medication and exercise can ease your pain and help keep your back strong.


Ankylosing spondylitis often starts in the sacroiliac joints, where your spine connects to your pelvis. The signs most commonly appear before age 45. You might notice:

  • Mild aches in your low back or buttocks that come and go
  • Pain that’s worse in the morning or after sitting for a long time
  • Inflexible spine that curves forward
  • Pain and stiffness in your shoulders, hips, hands, or even the Achilles tendon in your heel
  • Tiredness
  • Swelling in your joints
  • Pain in your thigh, foot, or heel

Symptoms of AS can differ from person to person. Your condition also may change quicker or slower than someone else’s.


AS can cause pain and inflammation in other parts of your body.

Eyes. About 40% of people with AS have an eye problem called uveitis. It’s a painful inflammation that can blur your vision and make you sensitive to bright light.

If you have uveitis, your doctor might check for AS even if you don’t have any symptoms for it.

Heart valve. It’s not common, but AS can enlarge the aorta, the largest artery in your body. This can change the shape of the aortic valve, which can allow blood to leak back into your heart. Your heart won’t pump as well, which can leave you tired and short of breath.  

Cancer. A large study found that people with AS are more likely to get certain types of cancers. They include bone and prostate cancers in men and colon cancer in women, as well as blood-related cancers in both sexes.



Researchers aren’t exactly sure what triggers AS. But they think it has a strong genetic root. Most people with AS have an antigen called HLA-B27. Doctors suspect the gene unleashes your immune system to attack certain common bacteria in your body and sets off AS symptoms.

Men are more likely than women to have AS, and it strikes them earlier and harder. Women tend to have a milder form of AS called non-radiographic axial spondyloarthritis. Anyone from children to seniors can get AS, but it often starts in your teens and young adulthood. 


AS can be tough to detect. That’s because back pain, its main symptom, is a complaint that many people have. Diagnosing ankylosing spondylitis may be even trickier for women because the disease is more common in men and because women’s symptoms can be different.

There’s also no single test to confirm AS. Your doctor may rely on your symptoms, physical exam, and blood tests to find out. You also might have an X-ray or an MRI. But this doesn’t always help because joint damage doesn’t show up right away on imaging tests.


Staying active is one of the keys to managing AS, and to keep it from worsening. Medications may help some people.

Exercise. The less you sit or lie down, the better you’ll feel. Exercise helps you stand straighter and keeps your spine limber. Staying active may even banish your pain without medication. 

Physical therapy. You can practice good posture, learn how to stretch tight muscles and keep your spine stable, and other techniques that can lower your pain. You can do them at home. But most people benefit more if you work with a professional therapist or with a group. 


Prescription nonsteroidal anti-inflammatory drugs (NSAIDs) like indomethacin (Indocin) help most people with AS. They can lead to stomach bleeding, heart problems, and other side effects.

If your condition is severe, your doctor may have you try stronger medications like biologics. These drugs are made with substances like proteins from living things. But they may cause serious side effects, including infections.

It’s hard to say how AS will affect you over time. Some people have mild backaches now and then. Others have symptoms that get worse as they grow older. That’s especially true for people who smoke or don’t respond to NSAIDs. But there’s no way to know for sure.

WebMD Medical Reference Reviewed by Tyler Wheeler, MD on October 18, 2019



Genetic and Rare Diseases Information Center (National Institutes of Health): “Ankylosing


Arthritis Foundation: “What Is Ankylosing Spondylitis.”

University of Maryland Medical Center: “A Patient’s Guide to Ankylosing Spondylitis.”

Spondylitis Association of America: “Overview of Ankylosing Spondylitis,” “Sex Differences in Ankylosing Spondylitis,” “Does the Microbiome Cause Ankylosing Spondylitis?”

American College of Rheumatology ( “Spondyloarthritis.”

Harvard Health Blog: “FDA strengthens warnings that NSAIDs increase heart attack and stroke risk.”
Rachel Caspi, senior investigator, National Eye Institute. “A to Z: Spondylitis, Ankylosing.”

UpToDate: “Clinical manifestations of axial spondyloarthritis (ankylosing spondylitis and nonradiographic axial spondyloarthritis) in adults.”

Brigham and Women’s Hospital: “Standard of Care: Ankylosing Spondylitis.”

Journal of Clinical Medicine Research (Canada): “Cardiac Involvement in Ankylosing Spondylitis.”

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