Rheumatoid arthritis usually causes joint pain and stiffness, but it can also cause issues with other body parts, including gastrointestinal concerns.

Rheumatoid arthritis (RA) is an autoimmune condition that develops when your immune system attacks healthy cells in your joints. Biological females have about a 3.6% lifetime risk of developing RA, and biological males have about a 1.7% risk, according to 2022 research.

People with RA are more likely than people in the general population to develop gastrointestinal (GI) concerns like diarrhea. Medications and factors linked to the condition itself may both play a role.

Disruptions in your gut microbiome are commonly associated with diarrhea. Recent evidence suggests gut imbalances may also contribute to the development of RA.

Read on to learn more about the connection between RA and diarrhea.

RA may increase your chances of developing diarrhea and other GI symptoms in several ways.

Rheumatoid arthritis medications

According to the Arthritis Foundation, disease-modifying antirheumatic drugs often cause digestive symptoms like diarrhea. They can also lower your immune function and may make you more prone to developing infections that may cause diarrhea.

Diarrhea can also be a side effect of nonsteroidal anti-inflammatory drugs and steroids used to manage RA. Most GI issues in people with RA are linked to chronic use of these medications, according to a 2021 research overview.

Other autoimmune diseases

Many people who have RA also have another autoimmune disease. Some other types of autoimmune diseases like Crohn’s disease or ulcerative colitis affect your GI system and cause symptoms like diarrhea.

In a 2017 study, researchers identified at least one other autoimmune condition in 24.3% of almost 300,000 people with RA. Only 10.5% of nearly 1 million people in the general population had an autoimmune condition.

The researchers found higher rates of several autoimmune conditions that affect the GI tract in people with RA:

Autoimmune diseaseRAGeneral populationIncreased risk
Crohn’s disease1.12%0.40%2.8 times
Ulcerative colitis1.12%0.27%2.1 times
Celiac disease0.23%0.14%1.7 times

Rheumatoid vasculitis and AA amyloidosis

Fewer than 1% of people with RA develop a complication called rheumatoid vasculitis. It usually occurs after you’ve had RA for a long time and can range from mild to life threatening.

It’s characterized by inflammation of small- or medium-sized blood vessels that can restrict blood flow to organs. Symptoms can include abdominal pain and diarrhea if your intestines are involved.

AA amyloidosis is a rare complication of chronic inflammatory diseases. It’s characterized by the buildup of proteins in your organs. It develops in about 0.6% to 1.1% of people with RA and causes GI symptoms in anywhere from 10% to 70% of people who have it.

Symptoms can include:

  • diarrhea
  • abdominal pain
  • acid reflex
  • GI tract bleeding, which can be life threatening

Disrupted gut biome

A growing amount of research suggests that disruptions to your gut microbiota might contribute to the development of RA. It’s also often associated with diarrhea.

According to a 2022 research review, disruptions in your microbiome seem to occur before symptoms of RA develop and continue to progress as the disease progresses. More research is needed to fully understand the link.

Diarrhea is common among the general population and may be more common in people with RA.

Anywhere from 10% to 38% of people with rheumatoid vasculitis have involvement in their intestines, which may lead to diarrhea.

In a 2020 study, researchers suggested that people with chronic diarrhea had a risk 1.7 times higher than the general population of developing RA. The association was 2.21 times higher for people who also smoked cigarettes.

Flare-ups in RA symptoms might occur at the same time as flare-ups in GI symptoms. Many autoimmune conditions have similar triggers, such as stress or certain foods.

These triggers might lead to increased symptoms for both RA and another autoimmune condition that causes GI symptoms.

RA can potentially cause many other GI symptoms. The symptoms you develop depend on the underlying cause. They can include:

You may want to contact a doctor any time you develop new symptoms that can indicate arthritis, such as:

  • pain, swelling, or stiffness in your joints
  • blood in your stool (which may appear bright red or dark brown, black or tar-like)
  • joint redness or warmth
  • trouble moving or performing daily activity

The Arthritis Foundation recommends seeing a doctor if you develop joint symptoms that last more than 3 days or if you have several episodes of symptoms within a month.

Prolonged diarrhea can cause dehydration and other severe symptoms. It’s a good idea to see a doctor if you don’t notice improvement after a couple of days.

People with RA seem to develop GI concerns, including diarrhea, more often than people in the general population. Medication side effects, coexisting autoimmune conditions, and complications of the disease itself may all play a role.

Emerging research also suggests that disruptions to your gut microbiome might contribute to the development of RA. Disruptions in your gut microbiome are also commonly associated with diarrhea.