What Is Ankylosing Spondylitis?

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Ankylosing spondylitis (AS) is a type of inflammatory arthritis that causes inflammation of the spine. It is an autoimmune disease, in which the immune system causes damage to the body's own tissues. If AS is not adequately treated, it could lead to fusion of the vertebrae (the small bones of the spine). 

AS is a progressive condition, which means it will get worse over time. Even so, the disease is manageable, and spinal fusion and other disease complications might be preventable. 

This article will cover AS symptoms, stages, causes, diagnosis, treatment, and more. 

Person sitting on edge of bed placing hands on their lower back

Kittiphan Teerawattanakul / EyeEm / Getty Images

Ankylosing Spondylitis Symptoms

The progression of AS symptoms can be measured in three stages—early, progressing, and advanced. As the disease progresses, you will experience different or worsening symptoms. 

Early Stage

In the earliest stage of AS, symptoms will come on gradually and worsen with time. 

Some of the earliest symptoms are:

  • Back pain: Back pain is one of the first symptoms people with AS experience. It typically starts at the sacroiliac (SI) joints, where the lumbar spine connects to the pelvis.
  • Back stiffness: Because it causes back pain, AS will lead to stiffness and reduced movement. With inflammation, pain increases with movement and when getting up and sitting down.
  • Fatigue: Fatigue is a main whole-body symptom of AS, affecting 50% to 70% of people with the condition. Fatigue occurs because the body is forced to work harder to fight inflammation.

Additional early symptoms of AS include:

  • Pain in the buttocks or SI joints 
  • Peripheral arthritis of the knees, ankles, shoulders, neck, and small joints of the hands and feet
  • Back pain that awakens you from sleep 
  • Back pain lasting 30 or more minutes after waking up
  • Pain and tenderness at the entheses, the areas where tendons and ligaments connect to bone.

Progressing Stage

As AS progresses, you might experience more pain and stiffness on both sides of the spine.

Some people with AS might also have severe symptoms affecting different body systems, including:

Advanced Stage

In advanced AS, a new bone formation called ankylosis occurs and causes the spinal column to fuse. Spinal fusion leads to limited spine mobility, kyphosis (the spine bending forward), and an increased risk for spinal fractures. 

Sex Differences

Ankylosing spondylitis was previously believed to primarily affect males, although newer studies have found all sexes are equally affected. AS might cause different symptoms in females and has a different progression. Females report more peripheral arthritis symptoms, fatigue, enthesitis, and comorbid conditions like IBD.

Females also have a longer delay in diagnosis than males.

(Note that when citing research, the terms for sex and gender from the source are used.)

What Causes Ankylosing Spondylitis?

Anyone can get AS, but certain risk factors might increase the likelihood of the disease. 

If other family members have AS or another autoimmune disease, you are more likely to get the disease. AS is also linked to the HLA-B27 mutated gene, which runs in families. HLA-B27 has been detected in 90% of people with AS. While this gene is a risk factor, it is possible to have it and never develop the condition.

Additional risk factors for AS are:

  • A history of frequent gastrointestinal infections 
  • Having another type of autoimmune arthritis 
  • Age, specifically AS commonly occurs in young people between age 17 and 45, but it can also affect children and adults over 45

What Triggers AS Symptoms?

AS causes both localized and generalized flares. Localized flares affect one primary area (usually the back) and cause pain, stiffness, and fatigue. Generalized flares are more severe and affect multiple areas of the body (i.e., the back, hips, knees, and ankles).

Triggers that might lead to a local or generalized AS flare-up include:

  • An illness or infection 
  • Chronic stress (mental or physical) 
  • Diet, including foods like red meat, junk foods, and sugary sweets, which can produce inflammation 
  • Not taking medicines correctly
  • Overactivity 

Tests Used to Diagnose Ankylosing Spondylitis

In diagnosing AS, a healthcare provider will ask about your symptoms, medical history, and family history. A physical exam of the spine, peripheral joints, and entheses will be done to look for areas of pain, tenderness, stiffness, and swelling. 

The healthcare provider will also request imaging to look for damage to bones and soft tissues of the spine. This might include an X-ray and magnetic resonance imaging (MRI). 

Blood work used to diagnose AS might include HLA-B27 genetic testing, blood marker inflammation testing, and tests to rule out other conditions, such as rheumatoid factor testing to rule out rheumatoid arthritis, a type of inflammatory arthritis affecting the linings of joints. 


AS is sometimes misdiagnosed because it causes symptoms that can be found in other joint and muscle diseases. 

Conditions that mimic AS include:

What Is the Typical Age of Diagnosis?

The onset of AS typically peaks in young adults in their 20s and 30s, with an average age of onset of 26 worldwide.

Even though diagnoses are common in young adulthood, anyone can develop AS, including children and older adults. It is rare, but some people can have a new symptom onset of AS after age 45.

Ankylosing Spondylitis Treatment

The main goals of treating AS are to relieve pain and stiffness and prevent or delay disease complications, including spinal deformity. A multifaceted approach, including medications, diet changes, lifestyle changes, and surgery as a last resort, can help you accomplish this.


Medications to treat AS include nonsteroidal anti-inflammatory drugs (NSAIDs), conventional disease-modifying anti-rheumatic drugs (DMARDs), and biologic DMARDs.

  • NSAIDs like Aleve (naproxen) and Advil (ibuprofen) can relieve pain, inflammation, and stiffness. These should be taken as directed by a healthcare provider because they can lead to gastrointestinal troubles.  
  • DMARDs like methotrexate slow down the inflammatory processes that lead to joint destruction. These drugs are typically prescribed to people with peripheral arthritis but do not treat spinal inflammation. 
  • Biologic drug therapies, including tumor necrosis factor (TNF) blockers and interleukin-17 (IL-17) inhibitors, are prescribed as injections or intravenous (IV) treatments. These drugs can tamp down the immune system to stop or slow inflammation.

Anti-Inflammatory Diet

Some foods, including junk and processed foods, can produce inflammation, which can lead to increased AS symptoms. You will want to reduce or eliminate these types of food and include more anti-inflammatory foods. 

Examples of anti-inflammatory foods are:

  • Almonds
  • Avocados 
  • Berries 
  • Cherries
  • Cruciferous vegetables (broccoli, cauliflower, kale, etc.) 
  • Extra virgin olive oil
  • Fatty fish (salmon, sardines, herring, mackerel, etc.)
  • Green tea


Most people with AS will never need surgery. Surgery is recommended if you have spine, hip, or other joint damage that needs repairing or replacement.

Lifestyle Changes

Your lifestyle choices might help you to manage AS. Some lifestyle choices that might help are:

  • Being active: Exercise can ease pain and keep your back and spine strong and flexible.
  • Not smoking: Smoking is generally bad for your help, but it might also increase AS disease activity or reduce the effectiveness of AS medicines. 
  • Practicing good posture: Managing AS and staying on top of your treatment plan can reduce stiffness and maintain your posture. Proper posture might also reduce symptoms of AS and bone and joint damage.  

Specialists Who Treat AS

A primary care provider may be the first medical professional you reach out to when you first experience symptoms of AS. They may request testing and make the diagnosis or refer you to a rheumatologist if they suspect AS.

A rheumatologist is a physician who specializes in diagnosing and treating conditions that attack the muscles and joints.

Additional specialists you might need to see as your AS progresses are:

Complications of Ankylosing Spondylitis

AS might lead to spinal fusion and immobility. As the disease gets worse, the spine will lose flexibility, and back pain will become more intense. 

Additional disease complications of AS are:

  • Heart disease
  • Gastrointestinal diseases like IBD
  • Lung problems
  • Cauda equina syndrome: Symptoms include leg pain and weakness, urinary and bowel dysfunction, and sexual dysfunction. If you experience symptoms of CES, you should call 911 or get to the nearest emergency room.
  • Amyloidosis: This is a rare complication of AS in which amyloid protein builds up in the tissues and organs, including the heart, liver, and kidneys. People with AS are 6 times more likely to develop amyloidosis.
  • Neck fracture: If you receive an injury to your head or neck, computed tomography (CT) scanning of the neck is indicated. This is to rule out fracture, as that can be missed by conventional X-ray and can lead to neurological damage.

Complications of AS might be preventable by following your treatment plan. Contact a healthcare provider if new symptoms come up or if you feel medications are not managing your symptoms. 

Can You Prevent Ankylosing Spondylitis?

Autoimmune diseases like AS are generally not preventable. Reducing some of your risk factors might be possible. For example, you can avoid smoking and practice a healthy lifestyle to reduce risk. 

But even with mitigating risk factors, having a family history and genetic disposition can still increase the risk of AS. Let your healthcare provider know if you have a family history of the condition or other risk factors. 

Living With Ankylosing Spondylitis

Living With AS has ups and downs and can cause more than just physical symptoms. It can also affect your emotional health and limit your social life. 

Even so, you can do plenty to ensure a happy and healthy life with AS, including seeking support from family, friends, a support group, or a mental health professional. There are also things you can do to better cope, including being active and managing stress. 

Outlook for Ankylosing Spondylitis

Ankylosing spondylosis symptoms will worsen over time. The disease is rarely disabling or life-threatening, but symptoms can interfere with your ability to enjoy life. 

Make sure you follow your treatment plan and take advantage of all the resources your doctor provides. Pain and inflammation are manageable, and disease complications and disability can be avoided.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Lana Barhum
Lana Barhum has been a freelance medical writer since 2009. She shares advice on living well with chronic disease.