What is ankylosing spondylitis (AS)?

An inflammatory arthritis of the spine

Ankylosing spondylitis (AS) is an inflammatory arthritis that primarily affects the spine. This means that the joints and ligaments in the spine become inflamed, causing pain and stiffness. AS is an autoimmune disease, which means your immune system attacks healthy tissue and cells.

The pain of AS usually begins in the lower back and over time can spread to the upper spine, chest, and neck. The hips, shoulders, and knees may also be affected. The severity of AS varies from person to person. Some people may only have lower back pain and stiffness sometimes, while others may have severe pain that lasts a long time. The pain of AS also may occur in acute, painful episodes (called flares), followed by periods of no pain (called remissions).

Who is affected by ankylosing spondylitis?

Ankylosing spondylitis symptoms

  • Pain and stiffness in the lower back
  • Pain and stiffness that are worse during periods of rest or inactivity and get better with exercise
  • Back pain at night or early morning
  • Feeling very stiff in the morning