Ankylosing Spondylitis Complications: Eyes, Neurological, and More

Ankylosing spondylitis (AS) is the inflammatory condition that can make mornings feel like you slept in a cardboard box. But AS isn’t just “a back problem.” Because inflammation can travel, it may affect the eyes, nerves, heart, lungs, gut, skin, and bones. The goal of this guide is simple: help you recognize the common complications, understand the red flags, and know what conversations to have with your care team.

Important: This is general information, not personal medical advice. If you have new or concerning symptoms, get evaluated.

Why AS can cause complications outside the spine

AS is a type of spondyloarthritis, which means it can involve more than joints. Inflammation may show up where tendons attach to bone (entheses), in the eyes, and sometimes in blood vessels or organs. Over time, AS can also change the structure of the spinenew bone can form, segments may fuse, and posture can shift. Those structural changes can increase the risk of nerve compression and fractures, especially when bone density is low.

One reason complications can feel random is that AS activity can wax and wane. A quiet month of back stiffness doesn’t automatically mean the rest of the body is off the hook. AS is also linked with other inflammatory conditionsespecially uveitis, psoriasis, and inflammatory bowel diseaseso clinicians often watch for symptoms that suggest those overlaps.

Eye complications: uveitis (iritis) is the big one

Uveitis (often anterior uveitis, also called iritis) is one of the most common extra-spinal complications of AS. It can come on quickly, often affects one eye at a time, and may recur.

How common is uveitis in AS? Estimates vary across studies and populations, but roughly 1 in 3 people with AS experience at least one episode over time. That’s common enough that any sudden painful red eye in someone with AS should be treated as a likely uveitis flare until proven otherwise.

What uveitis can feel like

• Sudden eye pain or deep ache
• Redness
• Light sensitivity
• Blurred vision
• Sometimes floaters

Why it matters: Uveitis is treatable, but it’s not a “wait-and-see” situation. Delayed care can increase the chance of complications that affect vision.

What to do

If you develop the symptoms aboveespecially sudden pain + redness + light sensitivityseek same-day medical evaluation (often urgent ophthalmology/eye care). Treatment may include prescription anti-inflammatory eye drops and, in some cases, systemic medications that also treat AS inflammation.

Doctors typically confirm uveitis with an eye exam. Treatment often starts with prescription anti-inflammatory drops (and sometimes drops that relieve painful spasm), with stronger therapy for severe or recurrent cases. If you get repeat episodes, your rheumatology team may adjust systemic treatment to reduce overall inflammatory activitybecause the eye is not a separate universe.

Neurological complications: from irritated nerves to rare emergencies

Most neurological problems linked to AS are mechanicalnerves get irritated or compressed because of inflammation, bony changes, or fractures. The symptoms can still be serious, so the pattern matters.

More common: nerve root irritation (radiculopathy)

This can look like sciatica or “pins-and-needles” symptoms:

• Shooting pain down an arm or leg
• Numbness or tingling
• Weakness (tripping more, weaker grip, difficulty climbing stairs)

Persistent or worsening symptoms deserve evaluation, particularly if you have a very stiff or fused spine.

Spinal stenosis

AS-related changes (new bone, thickened ligaments, posture shifts) can contribute to spinal stenosis, a narrowing that can press on nerves. People often describe leg heaviness, cramping, or numbness that worsens with standing/walking and improves with sitting or bending forward. Management can include physical therapy, medications, injections, or surgery in severe cases.

Rare but urgent: cauda equina syndrome

Cauda equina syndrome is a rare complication reported in advanced, longstanding AS. It can affect bladder/bowel function and leg strength. Treat the following as urgent/emergency symptoms:

• New trouble starting urination or new urinary incontinence
• New loss of bowel control
• Numbness in the inner thighs/groin (“saddle” area)
• Rapidly worsening leg weakness

A key AS safety point: a stiff or fused spine is more vulnerable to fractures and, in some cases, injury can be missed if symptoms are attributed to “just a flare.” If you have trauma plus new severe neck/back pain, new numbness/weakness, or trouble with coordination, seek urgent evaluation. Clinicians may use advanced imaging when warranted to rule out injury.

Bone and spine complications: fusion, posture changes, osteoporosis, fractures

AS can cause vertebrae to fuse and may lead to kyphosis (a forward-stooped posture). Fusion reduces flexibility and can change balance. At the same time, many people with AS develop low bone density (osteopenia/osteoporosis), which increases fracture risk.

Bone density can drop for several reasons: inflammation changes bone remodeling, pain can reduce activity, and some people avoid weight-bearing movement because it feels unsafe. The result is a frustrating combostiffness plus brittlenessthat raises fracture risk. Ask your clinician whether bone density testing, fall-risk assessment, or osteoporosis treatment makes sense for you based on disease duration, prior fractures, medications, and family history.

Why fractures can matter more in AS

A fused, stiff spine can behave like a long lever, so trauma that might be “minor” for someone else can cause more significant injury. If you have a fall or car accidentor sudden, severe spine painget checked promptly, especially if you notice numbness, weakness, or coordination changes.

Bone health basics that actually help

• Ask whether you need bone density testing.
• Keep strength training and weight-bearing activity in your routine (within your safe limits).
• Discuss calcium/vitamin D and osteoporosis medications if you’re at risk.

Heart complications: aorta, valves, and rhythm issues

Chronic inflammation in AS is linked with a higher risk of certain cardiovascular problems. AS-specific issues can include inflammation of the aorta (aortitis), changes near the aortic root, and sometimes aortic regurgitation (a leaky aortic valve). Electrical conduction problems and arrhythmias can also occur.

Bring up heart symptoms like persistent shortness of breath, chest discomfort, fainting, or frequent palpitationsespecially if your AS has been active for years. Your clinician may recommend targeted evaluation based on symptoms and overall risk factors.

Some cardiovascular changes can be subtle at first. Aortic valve issues may show up as a new murmur or gradually increasing shortness of breath. Conduction problems may feel like skipped beats or lightheadednessor be found incidentally on an EKG. If you have symptoms, your clinician may consider tests such as an electrocardiogram or echocardiogram.

Lung complications: stiff chest wall and uncommon scarring

If AS affects the joints where ribs attach, the chest wall may expand less. That can create a restrictive breathing pattern and reduce exercise tolerance. Some people with longstanding disease develop scarring at the top of the lungs (apical fibrosis), but it’s considered uncommon. Avoiding smoking is one of the most protective steps you can take.

Helpful habits for breathing and lung health include aerobic activity you can tolerate, posture work that keeps the chest open, and diaphragmatic breathing exercises. Because respiratory infections can feel worse when chest expansion is limited, it’s also smart to stay current on recommended vaccines and seek care if a cough or fever is lingering.

Gut, skin, kidney, and whole-body complications

Gut inflammation and IBD overlap

AS shares inflammatory pathways with Crohn’s disease and ulcerative colitis. Ongoing diarrhea, blood in stool, unexplained weight loss, or recurring abdominal pain should be evaluatedbecause treating gut inflammation can also improve overall disease control.

Psoriasis and skin changes

Psoriasis can occur alongside AS and may guide medication choices. Tell your clinician about persistent scaly patches, nail changes, or unexplained rashes.

Kidney considerations

Rarely, chronic inflammation is linked to kidney complications. More commonly, long-term NSAID use can stress kidneys in some people, which is why routine labs are part of safe care.

Fatigue, sleep, and mood

Fatigue can be a major AS complication all by itself. Inflammation, pain, and poor sleep can feed each other. Depression and anxiety are also more common in chronic inflammatory disease. Treating sleep and mental health is not “extra”it often improves pain coping and quality of life.

Reducing complication risk: the stuff that’s unglamorous but effective

• Control inflammation: Medications (NSAIDs, biologics, and other options) are chosen to reduce disease activity and protect functionwork with your rheumatology clinician on a plan you can actually follow.
• Move consistently: Mobility work supports posture; strength work supports bone and stability; aerobic activity supports heart and lungs. Consistency beats intensity.
• Take eye symptoms seriously: sudden painful red eye + light sensitivity = same-day evaluation.
• Protect the spine: treat falls and crashes as “worth checking,” especially with a stiff/fused spine or osteoporosis risk.
• Manage standard health risks: blood pressure, cholesterol, sleep apnea, smoking, and diabetes all matterchronic inflammation can raise the stakes.
• Keep monitoring: periodic labs, eye care as needed, and bone density testing when appropriate help catch issues early.

When to seek help right away

• Eye: sudden pain, redness, light sensitivity, or blurred vision
• Neurological: new bowel/bladder problems, saddle-area numbness, rapidly worsening leg weakness
• Trauma: fall/car crash with new or severe spine pain, especially if stiff/fused
• Heart/lungs: new chest pain, fainting, persistent palpitations, unexplained breathlessness
• Gut: blood in stool, severe belly pain, ongoing diarrhea, unexplained weight loss

Real-world experiences: what complications can feel like (about )

Complications are easier to understand when they sound like real life. The examples below are composite storiescommon patterns people describerather than any one person’s case.

“My eye went red overnight, and I assumed it was screen time.”

People with AS often describe uveitis as a one-eye surprise: pain that feels deeper than surface irritation, redness that doesn’t quit, and light that suddenly seems personal. Many say the first episode is the slowest to treat because it’s mistaken for allergies or “too much screen time.” After diagnosis, the script changes: “If my eye is red and light hurts, I call today.” The biggest practical win is having a planan eye clinic you can reach quickly, a note in your medical record about prior uveitis, and the confidence to say, “I have ankylosing spondylitis and sudden eye pain.” Sunglasses help you survive the ride to the appointment, but the real fix is prompt evaluation and prescription treatment.

“My legs got heavy on walks, and I thought I was just out of shape.”

When spinal stenosis or nerve compression develops, people sometimes notice a predictable “walking limit.” They start a stroll fine, then legs feel heavy, tingly, or crampedoften improving with sitting or leaning forward. Because it doesn’t always feel like classic back pain, some chalk it up to being out of shape. Many say progress came from naming the pattern, getting imaging when appropriate, and working with a physical therapist on hip mobility, core strength, posture, and pacing. A helpful mindset shift is treating symptoms as data: what makes them worse, what eases them, and how quickly they’re changing.

“Fatigue is the symptom nobody warned me about.”

AS fatigue is frequently described as different from “tired.” People talk about brain fog, reduced stamina, and needing more recovery time after normal tasks. Two themes show up again and again: fatigue improves when inflammation is controlled, and fatigue improves when sleep is treated like a medical priority. Many people find that small routine changesheat before bed, a gentle evening stretch, a supportive pillow setup, and limits on late-night scrollingreduce night pain and morning stiffness. Others benefit from addressing sleep apnea, mood, or anemia when present. Practically, people often do best when they plan their day like a phone battery: schedule the highest-demand tasks when energy is best, and build in short breaks before the battery hits zero.

“I’m carefulbut one fall made me rethink ‘minor injury.’”

People with a very stiff or fused spine often learn a different rulebook for trauma. Some feel “okay” right after a slip or fender-bender, then develop escalating neck/back pain lateror notice new tingling they didn’t have before. The takeaway isn’t fear; it’s strategy: after significant falls or collisions, it’s reasonable to get checked, especially if pain is severe, unusual, or paired with numbness/weakness. Many also focus on prevention that doesn’t feel dramatic: strength and balance work, good lighting and clear walkways at home, and bone health follow-up (including bone density testing when appropriate).

If these stories share a theme, it’s this: complications become less scary when you recognize early signs, have a plan, and treat routine care (movement, monitoring, and inflammation control) as part of living wellnot as punishment for having a body.

Conclusion

AS complications can involve the eyes, nerves, bones, heart, lungs, gut, skin, and overall energy. The best defense is early recognition, steady inflammation control, and the right monitoring. If something feels new, fast-changing, or “not like your usual AS,” trust that instinct and get checked.