The main symptom of ankylosing spondylitis is back pain and stiffness. The pain usually starts in the lower back or buttock (or the sacroiliac joints, made up of the joints between the base of the spine and the pelvis). This usually dull pain may spread up to the shoulders or neck or down to the thighs. The pain is often worst in the morning or after rest. Morning stiffness can last for at least half an hour and may continue for several hours. Exercise can improve the back pain and stiffness.

For a small number of people, the pain does not start in the back; rather, it starts in the hip, shoulder joint, or knee.

Each person with AS can experience different symptoms, but chronic lower back pain is the most common.

Other AS signs and symptoms include:

  • difficulty sleeping
  • enthesitis (inflammation of the places where ligaments and tendons attach to bone)
  • fatigue
  • inflammation of the aorta (a large blood vessel near your heart) - this symptom is relatively uncommon
  • pain and tenderness in other areas such as the hips, heels, ribs, shoulder blades, and shins
  • uveitis (eye inflammation that can cause blurred vision, eye pain and redness, and sensitivity to light)

Over time, the pain and stiffness of AS can lead to stooping forward and bad posture. The damage to the spine and other joints of the body can make it harder to move the spine or expand the chest, to do your daily activities, and to live a normal life.

People with AS may also have other related health conditions. See "Associated conditions" for more information.