Ankylosing Spondylitis and Fibromyalgia: What Is the Relationship?

Ankylosing spondylitis (AS) can be a complex condition. It can cause significant low back and hip pain and stiffness, severe fatigue, brain fog, sleep troubles, and more. Many people who live with AS also have fibromyalgia (FM), a musculoskeletal condition that causes widespread muscle pain. 

Having AS might increase your risk for fibromyalgia. And having both these conditions can be debilitating and life-altering. 

This article discusses the relationship between ankylosing spondylitis and fibromyalgia, including how to treat and manage the conditions together.

Connection Between Ankylosing Spondylitis and Fibromyalgia

Ankylosing spondylitis is a type of spondyloarthritis (SpA). SpA conditions are joint diseases that affect the spine and sacroiliac (SI) joints in the pelvis. These joint conditions also inflame the entheses, the places in the body where ligaments meet bones.

Many of these conditions are caused by the HLA-B27 genetic mutation, but having this mutation does not necessarily mean a person will get AS, and not having it does not mean you are immune from getting AS.

Fibromyalgia is a well-known musculoskeletal condition that causes widespread pain, fatigue, and sleep problems. It often co-occurs with inflammatory disorders like AS, psoriatic arthritis, and rheumatoid arthritis.

Researchers believe fibromyalgia amplifies pain sensations by affecting how the brain and spinal cord process pain signals. Females are more likely to have fibromyalgia than males.

AS and fibromyalgia are painful conditions, and they have a complicated relationship. It is possible to be misdiagnosed with one disorder when you actually have the other, and it is also possible to have both conditions. If misdiagnosis occurs, treatment isn’t beneficial. If you have both conditions, it is vital to recognize and treat both.

The research shows that FM is a frequent comorbidity (co-occurring condition) of sponyloarthritis conditions, especially in people who experience peripheral arthritis (arthritis in the large joints, such as the arms and legs). In people with fibromyalgia and a spondyloarthritis condition, disease activity might be overestimated, leading to increased and more aggressive treatment. 

According to a study published in 2021 in the journal Rheumatology, the estimated prevalence of coexisting FM in axial spondyloarthritis (axSpA) is 14%.

There are two main types of axApA, one of which is AS. The other type is non-radiographic axSpA (nr-axSpA), which does not cause the same spine damage as AS but can be a precursor to AS.

The study’s authors add the importance of considering misdiagnosis, as 50% of the people who fulfilled the criteria for fibromyalgia at baseline did not meet the criteria nearly two years later.

Ankylosing Spondylitis-Fibromyalgia Connection Risks  

A 2021 study found that people with AS have a higher risk for fibromyalgia, especially after age 65. It also noted that awareness of this connection could impact decisions about diagnosis, disease severity evaluations, and treatments. The authors noted that the greater risk for fibromyalgia with AS was due to central sensitization. 

AS also causes inflammation and chronic pain, which are considered risk factors for fibromyalgia. Even so, researchers still do not have conclusive information as to why AS and fibromyalgia might coexist. Still, they suggest healthcare providers be alert to the possible association between the two conditions.

While researchers do not have definitive answers as to why AS might co-exist with fibromyalgia, they have some theories about autoimmunity, inflammation, and fibromyalgia.

"Autoimmunity" means that the immune system has malfunctioned and turned against itself. When this happens, there is an abnormal inflammatory response that becomes chronic. Ongoing inflammation eventually starts to destroy healthy tissues. With AS, inflammatory attacks are focused on the spine and the SI joints.

FM is not an autoimmune disease because it does not cause typical inflammation. There is no evidence that fibromyalgia causes any damage to body tissues. It is challenging to diagnose fibromyalgia because many of its symptoms resemble other conditions, including autoimmune diseases, and fibromyalgia occurs alongside autoimmune disorders.

One 2019 International Journal of Molecular Sciences report outlined the common features of fibromyalgia and autoimmune disorders. These features include triggers and risk factors, such as:

• Infection and trauma triggers
• Pathogen risk factors: Epstein-Barr virus, herpes simplex virus, hepatitis C
• Inflammatory response after vaccination, silicone breast implantation, or mineral oil injections 
• Genetic risk factors that predispose someone to a specific autoimmune disorder
• Being female
• Family history 
• Occurring with other autoimmune disorders 
• Activation of the adaptive immune system—the part of the immune system that works to eliminate pathogens and prevent infection 
  

While fibromyalgia does not cause typical inflammation that is seen in autoimmune diseases, it leads to neuroinflammation—inflammation of nervous tissue (found in the brain, spinal cord, and nerves). Newer studies have confirmed the nervous system and immune system work together to cause neuroinflammation.

Common triggers and causes might explain the connection between AS and fibromyalgia. They might also explain the effect of having both conditions. 

In the previously mentioned 2021 Rheumatology study, the authors identify the importance of identifying fibromyalgia as they treat AS based on the current treatment guidelines. They further note people with axSpA and fibromyalgia report higher disease activity, depression, anxiety, fatigue, work interference, and lower quality of life than those with axSpA only. 

Treatment and Management of Ankylosing Spondylitis and Fibromyalgia 

AS and fibromyalgia might cause similar symptoms but have different underlying processes. Separate treatment is required for each condition. 

Ankylosing Spondylitis

Treatment for AS aims to relieve symptoms and delay or prevent spine damage and complications like spinal fractures, osteoporosis (progressive bone loss), heart disease, and eye inflammation. 

Medications used to treat AS include: 

• Nonsteroidal anti-inflammatory drugs (NSAIDs) such as Advil (ibuprofen) or Voltaren (diclofenac) to manage pain and inflammation 
• Corticosteroids to manage inflammation during flare-ups (periods in which AS symptoms are increased or new symptoms develop)
• Disease-modifying antirheumatic drugs (DMARDs) such as Azulfidine (sulfasalazine) and methotrexate for people with AS who experience pain and inflammation in joints other than the spine, including the arms and legs
• Biologic drugs such as Enbrel (etanercept), Cimzia (certolizumab), Cosentyx (secukinumab), Remicade (infliximab), and Simponi (golimumab) to suppress immune system activity, which can reduce AS disease activity and symptoms

Some people with AS need surgery to correct spinal deformities or joint problems. The type of surgery your healthcare provider recommends will depend on your affected body areas, pain and symptom severity, and overall health. 

Fibromyalgia

Treatment for fibromyalgia aims to manage pain and other symptoms to improve quality of life. Medications used in the treatment of fibromyalgia work to reduce pain and other symptoms. They might help to improve sleep as people with fibromyalgia suffer from poor sleep quality.

Fibromyalgia treatments include:

• Pain relievers, including Tylenol (acetaminophen) and Advil (ibuprofen) 
• Antidepressants like Cymbalta (duloxetine) and Savella (milnacipran) to reduce fibromyalgia pain and fatigue
• Muscle relaxers to manage muscle pain and spasms and promote sleep
• Anti-seizure drugs like Neurontin (gabapentin) to manage fibromyalgia pain 
  

Lifestyle Therapies for AS and FM

Some lifestyle strategies can help you to manage both AS and fibromyalgia. These include:

• Exercise and physical therapy: Many people with AS and fibromyalgia find that being active can help improve their pain levels and other symptoms like joint and muscle stiffness. People with AS and fibromyalgia might benefit from low-impact exercises such as walking, water activities, yoga, and stationary biking. A physical therapist can work with you to find appropriate exercises for managing strength and flexibility. 
• Meditation: Incorporating meditation into your day can help you to manage stress and pain levels. There are many online videos available or apps for your smartphone to help you get started. 
• Improved sleep: Since sleep plays an essential role in pain and mood regulation, it can also help you manage AS and fibromyalgia pain. Sleep improvements can include avoiding caffeine and exercise too close to bedtime, going to bed at the same time every night and getting up at the same time each morning, avoiding screen time at bedtime, and finding ways to relax before bed. 
  

AS and FM are painful conditions that can negatively affect your quality of life. Combined health care for these two conditions will help reduce pain, improve sleep and energy, and prevent AS from worsening.

People with AS could be under the care of a rheumatologist. That same doctor can help you to manage fibromyalgia.

Prevention 

Autoimmune diseases like AS are generally not preventable. Even with genetic testing, there is no way to determine who will go to develop the condition.  

Simply having an autoimmune disease like AS doesn’t mean someone will go on to have fibromyalgia. And much like AS, fibromyalgia cannot be prevented.

If you are being treated for AS and feel like your symptoms are not improving, or you are experiencing muscle pain and additional symptoms like severe fatigue, sleep troubles, and cognitive issues, let your healthcare provider know.

Similarly, your healthcare provider needs to know if you have been diagnosed with fibromyalgia and experience low back and hip pain. They can examine you and request testing to determine what is causing any additional symptoms.

Summary 

Ankylosing spondylitis and fibromyalgia are two different conditions. AS is an autoimmune disease that causes pain and inflammation of the spine and sacroiliac joints. fibromyalgia is a musculoskeletal condition that causes widespread muscle pain and symptoms like headaches, severe fatigue, mood problems, and sleep issues. 

AS and fibromyalgia share some similar symptoms and may have some underlying triggers and causes. But they are managed and treated differently. Treating AS requires managing the effects of an overactive immune system, while FM treatment focuses on pain and symptom management. 

Neither condition is preventable. Reach out to your healthcare provider if you have AS and start to experience symptoms of FM, including widespread muscle pain. You should also inform your healthcare provider if you have FM and develop low back or hip pain. 

A Word From Verywell

Ankylosing spondylitis is a condition known for causing pain in the spine and sacroiliac joints, but symptoms of AS do not stop here. People with AS can also experience inflammation and pain in their entheses, large joints, and organ systems (i.e., eyes and heart). 

If you find your AS symptoms are worsening or not improving with treatment, make an appointment to see your healthcare provider. They might suggest other treatment options that better manage symptoms, slow down the disease’s effects, and reduce the potential for disease complications like heart disease and eye inflammation problems. 

You also want to be aware of symptoms like paralysis and weakness, as these might indicate a severe complication of AS called cauda equina syndrome, in which the nerves of the low back suddenly become compressed. Getting immediate medical help for this condition improves your chances for a good outcome.