Seven less common, sometimes surprising signs and symptoms of Ankylosing spondylitis include the following:

1. Eye Redness, Pain, and Sensitivity to Light

“If you have AS and your eye turns red, see an ophthalmologist — this may be a sign of inflammation of the eye,” Pisetsky says.

About one-third of people with ankylosing spondylitis will experience inflammation of the eye, known as iritis or uveitis, at some point, notes the SAA. Symptoms to watch for include painful, red, or watery eyes; blurred vision; and sensitivity to bright light. Treatment may include corticosteroid eye drops to reduce the inflammation.

2. Abdominal Pain, Cramping, and Bowel Issues

Some people with ankylosing spondylitis also develop symptoms of bowel inflammation, such as abdominal pain, cramping, bloody stools, and diarrhea, notes the SAA, and they may also be diagnosed with an inflammatory bowel disease (IBD) such as ulcerative colitis or Crohn’s disease, Pistesky says.

However, bowel symptoms could also be a result of the underlying inflammation in ankylosing spondylitis, or they could be a side effect of the nonsteroidal anti-inflammatory drugs (NSAIDs) that many people with AS take to treat pain and inflammation.

People “may not realize symptoms such as diarrhea or cramping are related to AS, but it’s important to bring these symptoms to your doctor’s attention,” says Pistesky, adding that some of the same prescription drugs used to treat ankylosing spondylitis are also prescribed for IBD.

3. Shortness of Breath and Dizziness

Some people with ankylosing spondylitis develop heart problems due to high levels of inflammation throughout their body, says Susan Goodman, MD, a rheumatologist at the Hospital for Special Surgery and professor of medicine at Weill Cornell Medical College, both in New York City.

One possible heart condition is chronic inflammation around the aortic valve, called aortitis, per the SAA. “This is generally seen after years of disease,” Dr. Goodman says.

Aortitis and a variety of other heart problems can cause shortness of breath, dizziness, chest pain, and fatigue — all of them symptoms you should bring to your doctor’s attention if you have them.

People with ankylosing spondylitis may benefit from imaging tests to catch any signs of heart involvement early, according to a research review.

4. Pain in Joints Besides the Spine

Although ankylosing spondylitis symptoms most commonly affect the spine and surrounding area, any joint can be affected — including the hips, ankles, elbows, knees, shoulders, or even jaw, according to Goodman.

“The stiffness, inflammation, and pain can spread up the spine and into the neck and other places,” she says, adding that these symptoms are treated in a similar fashion to AS-related back pain. NSAIDs to reduce pain and inflammation, along with stretching and flexibility exercises, are often the first line of therapy.

5. Heel Pain

“With AS, there can be pain and tenderness in areas of the body where joints meet bone,” Goodman says. This condition is known as enthesitis, notes the Arthritis Foundation. Affected areas can include the Achilles tendon at the back of the heel and the plantar fascia at the base of the heel. “Treating the underlying AS can also benefit heel pain,” she says.

6. Chest Pain

It may feel like the crushing chest pain of angina or manifest as pain that occurs with deep breathing, but some people with ankylosing spondylitis do report chest symptoms, according to the SAA. With AS, the joints between the ribs and spine may become inflamed, which decreases the chest’s ability to expand.

You should have any chest pain evaluated by a doctor immediately to rule out other, possibly serious conditions such as a heart or blood vessel problem. If your chest pain is found to be related to ankylosing spondylitis, you may benefit from working with a physical therapist or respiratory therapist.

RELATED: What to Do if Ankylosing Spondylitis Affects Your Ribs

7. Fatigue

For some people with ankylosing spondylitis, fatigue can be overwhelming. “It’s a very nonspecific symptom, but it can signal that something inflammatory is going on in the body,” Goodman says.

General malaise, or a sense of being unwell, can also be a symptom of the inflammatory process. “Pain can make you tired, and people with AS may have trouble sleeping comfortably, which can add to fatigue,” she adds.

These seven symptoms represent only some of the potential effects of AS in the body. It’s important to let your doctor know about any new symptoms, since they may be a result of ankylosing spondylitis or its treatment, and some symptoms may need to be evaluated by a specialist.

Additional reporting by Quinn Phillips.