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Arthritis Health Center

What Is Ankylosing Spondylitis?

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Ankylosing spondylitis (AS) is a type of arthritis that causes lower back pain and stiffness.

Back pain from AS is not the same as more common types of back pain caused by things such as muscle spasms or slipped discs. AS back pain is caused by inflammation. It’s chronic, which means it is not a onetime thing. You will have it for a long time, but there are treatments to help lessen pain and stiffness. To get started, your doctor will look for some of these signs of inflammatory back pain.

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  • Ongoing back pain that is more likely to start when you are young (in your 20s and 30s).
  • Your back pain lasts for 3 months or more (making it chronic).
  • Your pain is worse after rest.
  • Your pain tends to get better when you exercise or move around.
  • Anti-inflammatory drugs (like acetaminophen or ibuprofen) ease your pain and stiffness.

Who Gets AS?

AS tends to start between your teens and 30s. Men are two to three times more likely to get the disease than women. You can inherit it from your family. One gene, called HLA-B27, is common in people with AS.

What Are the Symptoms of AS?

AS usually affects the joints in your spine. Your first signs of AS may be low back pain and stiffness. You may feel symptoms before doctors can see AS on an X-ray. That can take up to 5 years. AS often causes inflammation in the tendons that attach your spine’s bones to muscles.

  • You may feel pain or have swelling in other joints like your hands, ribs, hips, shoulders, or feet from arthritis.
  • It can also affect other organs like your eyes, heart, skin, or intestines.
  • You may also feel tired.

Over many years, AS can cause new bone to grow on your spine, fusing the vertebrae making it harder to move. This can cause severe stiffness. About half the people who have AS develop osteoporosis, or brittle bones.

Axial and Peripheral AS

There are different forms of the disease. Lower back pain means you have axial AS. Pain and swelling in joints other than your spine is called peripheral AS.

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