Ankylosing spondylitis (AS) is a type of arthritis that causes inflammation in the joints of your lower back. Over time, it can damage all of the joints and bones of your spine.

Pain and stiffness in your lower back and buttocks are the main symptoms of AS. But this disease can also cause long-term problems in other parts of your body, including your eyes and heart.

Your body tries to heal damage from AS by making new bone. These new segments of bone grow in between the vertebrae of your spine. Over time, the bones of your spine can fuse into one unit.

The joints between your spinal bones give you a full range of motion, allowing you to bend and turn. Fusion makes the bones stiff and hard to move. The extra bone can limit movement in the lower part of your spine, as well as the movement of the mid and upper spine.

AS causes your body to make new bone formations. These formations cause fusion (ankylosing) of the joints of the spine. The new bone formations are also weak and can easily fracture. The longer you’ve had AS, the more likely it is you might fracture a bone in your spine.

Osteoporosis is very common in people with AS. More than half of people with AS have this bone-weakening disease. Your doctor can help strengthen your bones and prevent fractures by prescribing bisphosphonates or other medications.

Although your eyes are nowhere near your spine, inflammation from AS can affect them, too. The eye condition uveitis (also called iritis) affects between 33 and 40 percent of people with AS. Uveitis causes swelling of the uvea. This is the layer of tissue in the middle of your eye underneath your cornea.

Uveitis causes redness, pain, distorted vision, and sensitivity to light, usually in one eye. It’s a serious condition that can lead to glaucoma, cataracts, or permanent vision loss if left untreated.

Your eye doctor will prescribe steroid eye drops to decrease the inflammation in your eye. Steroid pills and injections are also an option if the drops don’t work.

Also, if your doctor prescribes a biologic drug to treat your AS, it can also be used to treat and possibly prevent future episodes of uveitis.

Like other forms of arthritis, AS causes swelling in joints like the hips and knees. Over time, damage can make these joints stiff and painful.

Every time you breathe, your ribs expand to give your lungs enough room inside your chest. When the bones of your spine fuse, your ribs become more rigid and are unable to expand as much. As a result, there’s less space in your chest for your lungs to inflate.

Some people also develop scarring in the lungs that limits their breathing. Damage to the lungs can make it harder to recover when you get a lung infection.

If you have AS, protect your lungs by not smoking. Also, ask your doctor about getting vaccinated against lung infections like the flu and pneumonia.

Inflammation can also affect your heart. Up to 10 percent of people with AS have some form of heart disease. Living with this condition increases your risk of a heart attack or stroke by up to 60 percent. Sometimes heart problems start before AS is diagnosed.

Cardiovascular disease

People with AS are at increased risk for cardiovascular disease (CVD). If you have CVD, you’re more likely to have a heart attack or stroke.

Aortitis and aortic valve disease

AS can cause swelling in the aorta, the main artery that sends blood from your heart to the rest of your body. This is called aortitis.

Inflammation in the aorta can prevent this artery from carrying enough blood to the body. It can also damage the aortic valve — the channel that keeps blood flowing in the right direction through the heart. Eventually, the aortic valve may narrow, leak, or fail to work properly.

Medications can help control inflammation in the aorta. Doctors treat a damaged aortic valve with surgery.

Irregular heart rhythm

People with AS are more likely to have a fast or slow heartbeat. These irregular heart rhythms prevent the heart from pumping blood as well as it should. Medications and other treatments can bring the heart back to its normal rhythm.

Here are some ways you can protect your heart if you have AS:

  • Control conditions that damage your heart. Treat diabetes, high blood pressure, high triglycerides, and high cholesterol with diet, exercise, and medication if you need it.
  • Stop smoking. The chemicals in tobacco smoke damage the lining of your arteries and contribute to the buildup of plaques that can lead to a heart attack or stroke.
  • Lose weight if your doctor says you’re overweight. People who are overweight or obese have more heart disease risks like high blood pressure and high cholesterol. The extra weight also puts more strain on your heart.
  • Exercise. Your heart is a muscle. Working out strengthens your heart in much the same way that it strengthens your biceps or calves. Try to get at least 150 minutes of moderate-intensity aerobic exercise each week.
  • Ask your doctor whether you should take TNF inhibitors. These drugs treat AS, but they also increase cholesterol levels, which contribute to heart disease.
  • See your doctor regularly. Have your blood sugar, blood pressure, cholesterol, and other numbers checked. Ask if you need an echocardiogram or other diagnostic tests to look for problems with your heart.

This rare complication happens when there is pressure on a bundle of nerves called the cauda equina at the bottom of your spinal cord. Damage to these nerves causes symptoms like:

  • pain and numbness in your lower back and buttocks
  • weakness in your legs
  • loss of control over urination or bowel movements
  • sexual problems

See your doctor as soon as possible if you have symptoms like these. CES is a serious condition.

The best way to avoid these complications is to get treated for your AS. Medications like NSAIDs and TNF inhibitors bring down inflammation in your body. These drugs can help prevent damage to your bones, eyes, and other parts of your body before it can cause long-term problems.