Ankylosing spondylitis (AS) is a type of inflammatory arthritis that primarily affects the spine but can also affect other body tissues. In AS, gastrointestinal inflammation may lead to bloating.

The gastrointestinal (GI) inflammation that can occur in AS may be due to the disease or a side effect of the medications that help treat the condition.

This article explains the association between AS and gut health and considers how people with AS can help treat or manage bloating and other GI symptoms.

A person with ankylosing spondylitis holding their stomach due to bloating.-2Share on Pinterest
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The Spondylitis Association of America (SAA) outlines an association between AS and inflammation of the GI tract, even in people without GI symptoms.

According to the SAA, up to 60% of people with AS have GI inflammation despite having no symptoms. Doctors may see signs of GI inflammation during a colonoscopy — a procedure that uses an internal camera to investigate the GI tract.

Among people who receive a diagnosis of AS, the SAA suggests around 3% to 4% already have irritable bowel disease (IBD). Around 10% will develop IBD more than 20 years after their AS diagnosis.

According to Creaky Joints, a charity based in the United Kingdom, the reason for the association between AS and IBD remains unclear. However, some scientists speculate that a change in gut bacteria may trigger inflammation in the GI tract and joints.

Common symptoms of IBD include:

Learn all about AS.

Medication side effects

According to the National Health Service (NHS) in the United Kingdom, GI issues may occur as a side effect of AS medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs).

According to the SAA, people with AS sometimes require high doses of NSAIDs to alleviate their symptoms, but these medications can cause significant GI side effects, such as:

Learn whether changing medications can cause new AS symptoms.

According to the SAA, people who take NSAIDs to help treat their AS can take other medications to help reduce GI side effects. Some medications to consider include:

  • antacids to help neutralize stomach acid or prevent the overproduction of stomach acid
  • sucralfate (Carafate) to help coat and protect the stomach
  • misoprostol (Cytotec) to help restore lost mucus

Alternatively, doctors may recommend a different class of NSAIDs called COX-2 inhibitors. The SAA suggests these are less likely to cause GI complications.

Anyone who thinks a particular AS medication is causing bloating or other GI issues should notify their doctor. It is important that they do not stop taking a medication or adjust the dosage unless their prescribing doctor says it is safe to do so.

Learn more about ankylosing spondylitis treatments.

General IBD treatments

Treatment for IBD may depend on its severity and the part of the GI tract it affects. Doctors may treat the condition using one or more of the following types of medication:

  • Aminosalicylates: These are medications that help decrease inflammation of the intestinal wall in ulcerative colitis.
  • Corticosteroids: Corticosteroids help suppress the immune system, reducing GI inflammation. However, due to the risk of other side effects, they are only suitable for short-term use during IBD flare-ups.
  • Immunomodulators: Medications that modulate the activity of the immune system so that it cannot cause persistent inflammation.
  • Biologic therapies: Biologics may help treat moderate to severe IBD that does not respond to other treatments. Doctors also use them to help treat AS.

A person with AS can discuss their IBD treatment options with a doctor.

Learn how biologics work for AS.

A person’s doctor can work to create a plan for managing GI issues due to AS, such as bloating. As part of this plan, a doctor may recommend certain dietary changes, such as:

The United Kingdom’s National Health Service (NHS) offers the following general tips to help reduce bloating:

  • exercise regularly to aid digestion
  • eat little and often
  • drink plenty of water
  • chew with the mouth closed to avoid swallowing air
  • massage the stomach from right to left to help release trapped wind

Learn 18 ways to reduce bloating.

A person should speak with a doctor if they have AS and develop bloating or other GI symptoms.

The doctor may assess a person’s treatment plan to determine whether bloating is caused by medications. They may also run tests to check for GI inflammation and possible IBD.

AS is an inflammatory condition that primarily affects the spine but can also cause inflammation in other parts of the body. In AS, inflammation of the GI tract can lead to bloating.

Research also suggests a link between AS and IBD, which can cause GI issues. Some people may experience bloating and other GI symptoms as a side effect of medications to treat AS.

Anyone with AS who experiences bloating should speak with a doctor, who will examine the cause and recommend appropriate treatments. A person should not change their existing treatment plan unless their doctor says it is safe to do so.