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Ankylosing spondylitis (AS) is an inflammatory disease that causes arthritis (swelling and stiffness of the joints) in your spine. When you have it, your vertebrae slowly fuse and your spine becomes less flexible.

The joint between your hip and spine (called your sacroiliac joint) may also wear away over time. The word "ankylosing" means stiff or rigid. "Spondyl" means spine, and "itis" refers to inflammation.

The inflammation of AS can often cause "hot spots" in your body. These can happen where your ligaments and tendons attach to your bone, or the entheses.

Commonly, this causes inflammation in your heels (Achilles tendinitis), the bottoms of your feet (plantar fasciitis), the outside of your hips (trochanteric bursitis), and along your breastbone (costochondritis). A less common form, called peripheral spondyloarthritis, causes pain and swelling in the large joints of your arms and legs along with inflammation of your spine.

AS is progressive, which means it gets worse over time. This happens because continued inflammation in your spine damages it, and bone fuses together between your vertebrae.

As more damage happens, more bone fuses together, and you get less flexible and mobile.

You're more likely to get an AS diagnosis between ages 17 and 35. Research suggests it may happen equally in men and women. And it's three times less likely in Black people than in white people. But when Black people have AS, it's more likely to be severe than it is in white or Latino people.

Although experts don't know exactly what causes it, genes seem to be involved. Along with being more common in some ethnic groups, it also tends to run in families. Studies show that nearly 90% of people who get the disease have a specific gene called HLA-B27. Researchers have developed a blood test to test for the HLA-B27 gene.

This test doesn't tell doctors if you have AS, but it helps them identify if you have this risk factor. Having HLA-B27 doesn't mean you'll get AS, and testing negative for the gene doesn't mean you won't.

Yes, but its first signs of inflammation usually happen in your sacroiliac joints. They're at the base of your spine, where it joins your pelvis. Your spine typically gets involved next.

But AS isn't just a disease of the bones and joints. Other parts of your body such as your GI system, eyes, and organs like your heart can have symptoms, too.

In the early stages of AS, you may have pain in your:

Usually these symptoms start gradually and get worse. They may even come and go for weeks or months at a time. Your back pain may be worse in the morning and get better through the day. Exercise can help relieve it, while rest can make it more painful.


Common complications of AS are eye inflammation and pain, called uveitis or iritis, that cause redness, blurry vision, and sensitivity to light. See your doctor right away if you have these symptoms.


Fusing of your vertebrate can cause stooped shoulders and a stiff spine. It's also common for AS to cause neck pain and lower back pain.


Some people with AS get psoriasis, which causes scaly, itchy, red patches on the skin.


When AS affects the joints that connect your ribs, it can be hard to take a deep breath.


AS can increase your risk for inflammation of your aorta, your heart's main artery to the rest of your body. That can lead to problems with your aortic valve and keep your heart from working the way it should.

Bowels and bladder

You're more prone to having inflammatory bowel disease (IBD) with AS, which can cause diarrhea and GI pain. Nerve damage may make it hard to control your bladder or bowel movements.

Hips, knees, and ankles

AS can make joints like your hips, knees, and ankles inflamed and painful. You may begin to have a harder time getting around once this happens.

Because your spine is usually most affected by AS, many symptoms are concentrated in and around it. Vertebral fusion can cause pain all along your spine, including your neck and lower back. You'll notice it's harder to move around easily. You'll become less flexible as this calcification happens.

Over time, AS can curve your spine forward, which can give you a stooped posture. You may also find it harder to sit in chairs as AS affects your pelvis. For those giving birth, pain, bone fusion, and stiffness in your hips can make vaginal delivery very difficult.

Nearly half of people with AS have osteoporosis, a condition that causes brittle bones. This also raises your risk of spinal fractures. Your jaw may also feel the effects of skeletal system inflammation. This can make it harder to chew food.

You can have symptoms anywhere you have joints. That includes painful, stiff knees, ankles, and feet. If these joints are damaged enough, you may need joint replacement surgery.

When you have AS, you're at higher risk of glaucoma. That's a group of eye conditions caused by damage to your optic nerve. Glaucoma can cause you to have blurry or blank spots in your vision, halos around light, and eye pain.

More than 40% of people with AS have symptoms in their eyes. Inflammation in your eye can cause uveitis, or swelling and redness in the front part of your eye. Usually, only one of your eyes has it at a time. Uveitis causes pain and sensitivity to light (photophobia).

Sexual dysfunction is common in males and females with AS. That may be linked to fatigue, stiffness, and pain common to the disease. Cauda equina syndrome may also cause problems with sexual feeling and function. Compressed or inflamed nerves can have trouble sending the information your body needs to feel sensation, or to get and keep an erection.

There's a high rate of erectile dysfunction in AS.

When you have AS, your risk of cardiovascular disease goes up. That includes different problems with your heart, including:

  • Aortitis (inflammation of your aorta, the large artery that carries blood away from the heart to the rest of your body)
  • Enlarged aorta
  • Heart arrhythmias (your heart beats irregularly, or too fast or too slow)
  • Cardiomyopathy (weakened heart muscle)
  • Ischemic heart disease (narrowed heart arteries that can cause pain and pressure in your chest, and may make you less able to exercise)

Anemia, or low red blood cell count, is common when you have AS. It causes symptoms such as weakness, feeling cold, and pale skin. You may also feel tired, which could be caused by chronic inflammation and pain related to AS, or be a symptom of anemia.

As your AS progresses, the bones in your chest may start to fuse. That can make it hard for your lungs to expand fully, or for you to take a full breath. It can cause you to have chest pain (called costochondritis).

Some people with severe AS get scarring at the top of their lungs. AS can also make it harder for you to heal from colds and other respiratory infections.

AS can also make it harder for you to heal from colds and other respiratory infections.

Your risk of depression and anxiety more than doubles when you have AS.

It's common to feel tired a lot of the time when you're living with a chronic illness and inflammation. It's not the type of fatigue that goes away after sleep. Talk to your doctor about ways you can conserve and build up more energy.

You may find it harder to sleep because of your symptoms. Pain can keep you up at night and rob you of rest. Lack of sleep can increase both physical and mental symptoms of AS.