Most Common Symptoms

Learn more about mechanical vs. inflammatory back pain

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It is important to note that the course of ankylosing spondylitis (AS) varies greatly from person to person. So too can the onset of symptoms. Although symptoms usually start to appear in late adolescence or early adulthood (ages 17 to 45), symptoms can occur in children or much later in life.

The most common early symptoms of AS are frequent pain and stiffness in the lower back and buttocks, which comes on gradually over the course of a few weeks or months. At first, discomfort may only be felt on one side, or alternate sides. The pain is usually dull and diffuse, rather than localized. This pain and stiffness is usually worse in the mornings and during the night, but may be improved by a warm shower or light exercise. Also, in the early stages of AS, there may be mild fever, loss of appetite, and general discomfort. It is important to note that back pain from AS is inflammatory in nature and not mechanical.

The pain typically becomes persistent (chronic) and is felt on both sides, usually lasting for at least three months. Over the course of months or years, the stiffness and pain can spread up the spine and into the neck. Pain and tenderness spreading to the ribs, shoulder blades, hips, thighs, and heels is possible as well.

Note that AS can present differently at onset in some people. This tends to be the case in women more than men. Quoting Dr. Elaine Adams, "Women often present in a little more atypical fashion so it's even harder to make the diagnosis in women." For example, we have heard anecdotally from some women with AS that their symptoms started in the neck rather than in the lower back.

Varying levels of fatigue may also result from the inflammation caused by AS. The body must expend energy to deal with the inflammation, thus causing fatigue. Also, mild to moderate anemia, which may also result from the inflammation, can contribute to an overall feeling of tiredness.

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Other Symptoms

In a minority of individuals, pain does not start in the lower back, or even the neck, but in a peripheral joint such as the hip, ankle, elbow, knee, heel, or shoulder. This pain is commonly caused by enthesitis, inflammation of the site where a ligament or tendon attaches to bone. Inflammation and pain in peripheral joints is more common in juveniles with AS. This can be confusing since, without the immediate presence of back pain, AS may look like some other form of arthritis.

Many people with AS also experience bowel inflammation, which may be associated with Crohn's disease or ulcerative colitis.

AS is often accompanied by iritis or uveitis (inflammation of the eyes). About one-third of people with AS will experience inflammation of the eye at least once. Signs of iritis or uveitis are: Eye(s) becoming painful, watery, and red, blurred vision, and sensitivity to bright light.

More information on complications of AS, including iritis/uveitis

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