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Ankylosing spondylitis


Ankylosing spondylitis (AS) is a long-term type of arthritis. It most commonly affects the bones and joints at the base of the spine where it connects with the pelvis.

These joints become swollen and inflamed. Over time, the affected spinal bones join together.

Alternative Names

Spondylitis; Spondyloarthropathy


The cause of ankylosing spondylitis is unknown. Genes seem to play a role.

The disease most often begins between ages 20 and 40, but it may begin before age 10. It affects more males than females.


The disease starts with low back pain that comes and goes. Low back pain is present most of the time as the condition progresses.

  • Pain and stiffness are worse at night, in the morning, or when you are less active. The discomfort may wake you from sleep.
  • The pain often gets better with activity or exercise.
  • Back pain may begin in the sacroiliac joints (between the pelvis and spine). Over time, it may involve all or part of the spine.
  • Your lower spine becomes less flexible. Over time, you may stand in a hunched forward position.

Other parts of your body that may be stiff and painful include:

  • The joints between your ribs and breastbone, so that you cannot expand your chest fully
  • Swelling and pain in the joints of the shoulders, knees and ankles
  • Swelling and redness of the eye

Fatigue is also a common symptom.

Less common symptoms include:

  • Loss of appetite
  • Slight fever
  • Weight loss

Ankylosing spondylitis may occur with other conditions, such as:

  • Psoriasis
  • Ulcerative colitis or Crohn disease
  • Chronic eye inflammation (iritis)

Exams and Tests

Tests may include:

  • CBC
  • ESR (a measure of inflammation)
  • HLA-B27 antigen (which detects the gene linked to ankylosing spondylitis)
  • X-rays of the spine and pelvis
  • MRI of the spine and pelvis


Your health care provider may prescribe drugs (NSAIDs) to reduce swelling and pain.

  • Some NSAIDs can be bought over-the-counter (OTC), such as aspirin, ibuprofen (Advil, Motrin), and naproxen (Aleve, Naprosyn).
  • Other NSAIDs are prescribed by your provider.
  • Talk to your provider or pharmacist before using any over-the-counter NSAID.

You may also need stronger medicines to control pain and swelling, such as:

  • Corticosteroid therapy (such as prednisone) used for short periods of time
  • Sulfasalazine
  • A TNF-inhibitor (such as etanercept, adalimumab, infliximab, certolizumab or golimumab)

Surgery may be done if pain or joint damage is severe.

Exercises can help improve posture and breathing. Lying flat on your back at night can help you keep a normal posture.

Outlook (Prognosis)

The course of the disease is hard to predict. Most people are able to function unless they have a lot of damage to the hips. Treatment with NSAIDS often reduces the pain and swelling. Treatment with TNF inhibitors appears to slow progression of the spine arthritis.

Rarely, people may have problems with:

  • Abnormal heart rhythm
  • Scarring or thickening of the lung tissue
  • The aortic heart valve
  • Inflammation in the large intestine (colitis)
  • Inflammation in the eye (iritis)
  • Psoriasis, a chronic skin disorder

When to Contact a Medical Professional

Call your health care provider if:

  • You have symptoms of ankylosing spondylitis
  • You have ankylosing spondylitis and develop new symptoms during treatment


Callhoff J, Sieper J, Weiß A, et al. Efficacy of TNFa blockers in patients with ankylosing spondylitis and non-radiographic axial spondyloarthritis: a meta-analysis. Ann Rheum Dis. 2014. PMID: 24718959

Inman RD. The spondyloarthropathies In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 265.

Sieper J, van der Heijde D, Landewé R, et al. New criteria for inflammatory back pain in patients with chronic back pain: a real patient exercise by experts from the Assessment of SpondyloArthritis international Society (ASAS). Ann Rheum Dis. 2009; 68:784. PMID: 19147614

Yu D, Lories R, Inman RD. Pathogenesis of ankylosing spondylitis and reactive arthritis. In: Firestein GS, Budd RC, Gabriel SE, et al, eds. Kelley's Textbook of Rheumatology. 9th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 74.

Review Date: 1/20/2015
Reviewed By: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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