Experts consider ulcerative colitis (UC) an autoimmune disease. An overactive immune response causes the immune system to attack healthy tissue in the gut, leading to inflammation of the large intestine.

Some medications people with UC take also compromise the immune system. However, this does not necessarily mean a person with ulcerative colitis has a higher risk of infection, including with the virus that causes COVID-19.

This article looks at the link between the immune system and UC, whether UC increases the risk of infection, and how treatments work to manage the condition.

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A 2020 study refers to UC as an immune-mediated disease, which means the researchers consider the condition an autoimmune disease. UC can cause the immune system to be overactive, but managing the condition does not suppress the immune system.

An autoimmune disease happens when a person’s immune system becomes overactive and attacks their healthy tissue. In UC, an overactive immune system attacks the intestines, causing inflammation in the large intestine.

If a person cannot manage their condition correctly, UC may lower their immune system’s overall function. Excessive immune activity in the gut could mean less immune activity in the rest of the body.

The following table shows a list of immunosuppressive drugs that can help treat inflammatory bowel disease (IBD) — which includes UC and Crohn’s disease — as well as drugs that do not suppress the immune system:

Immunosuppressant treatment for IBDIBD treatments that do not suppress the immune system
Steroids: Prednisone and budesonide5-aminosalicylates (5-ASA): Mesalamine, balsalazide, olsalazine, sulfasalazine
Immunomodulators: Azathioprine, 6-mercaptopurine, methotrexateAntibiotics: Ciprofloxacin, metronidazole
Anti-tumor necrosis factor (TNF): Infliximab, adalimumab, golimumab, certolizumab pegolDietary interventions: Elemental diet
Anti-IL12/23: Ustekinumab
Anti-integrin: Vedolizumab (Entyvio), natalizumab
Janus kinase (JAK) inhibitor: Tofacitinib

According to a 2021 review, the current evidence suggests people with IBD are not at higher risk of COVID-19 than the general population.

Immunomodulators and biologics help control an overactive immune response that causes inflammation in the gut. However, biologics are less likely to raise a person’s risk of infection because the medications are more targeted than immunomodulators, but they can still increase the risk of certain infections.

The American College of Gastroenterology (ACG) adds that most people taking standard IBD therapies do not have a higher risk of getting COVID-19. The ACG lists the following statements that a person with IBD may find useful regarding COVID-19:

  • Researchers believe that if a person keeps their IBD in remission, it is protective against COVID-19.
  • If a person manages their IBD successfully and does not require steroids or hospitalization, it can put less strain on the existing supply of medical resources.
  • A person should keep taking their IBD medications as a doctor has prescribed.

A 2021 review found that treatments for IBD did not increase the risks of COVID-19 complications, except for people taking 5-ASA and steroids.

In people with IBD who tested positive for COVID-19, 27% of people required treatment in a hospital, and mortality rates were less than 5%.

Negative outcomes were higher in people with UC than in Crohn’s disease. This may be because people with UC were more likely to be older and more likely to be taking 5-ASA than those with Crohn’s disease.

Researchers also found that taking biologics reduced negative outcomes.

Two of the current COVID-19 vaccines available in the United States are mRNA vaccines. According to the Crohn’s and Colitis Foundation, mRNA vaccines:

  • cannot cause COVID-19, as they do not contain the live virus that causes COVID-19
  • do not affect DNA in any way
  • cannot cause or worsen IBD

In a position statement on COVID-19 vaccines, the Crohn’s and Colitis Foundation states:

  • Non-live vaccines are safe for people with IBD, no matter what type of IBD treatment they receive.
  • Certain types of immune-modifying medications may cause a reduction in vaccine immune response, but this should not be a reason for delaying vaccination.
  • If people are taking systemic corticosteroids, they can check with their healthcare professional about a possible decrease in COVID-19 vaccine effectiveness.
  • Current vaccines with Food and Drug Administration (FDA) approval are safe for people with IBD who are pregnant, planning to become pregnant, or are lactating.

The foundation encourages people with IBD to discuss any concerns about getting a COVID-19 vaccine with their healthcare professional and decide whether they should it based on their individual case.

For more guidance on avoiding transmitting and acquiring COVID-19, people can follow the prevention strategies from the Centers for Disease Control and Prevention (CDC).

Keeping symptoms of UC in remission can help protect against infection with the virus that causes COVID-19. Therefore, it is important a person knows how to manage their condition.

A doctor can provide the most accurate and individualized information. Some treatment methods a doctor may recommend could include:

Medications

  • 5-ASA: These medications target the lining of the gastrointestinal tract to reduce inflammation. They are effective for the treatment of mild to moderate UC and help prevent relapses.
  • Corticosteroids: These medications suppress the whole immune response and treat moderate to severe UC. Corticosteroids can cause short- and long-term side effects and are generally only used to treat acute inflammation before switching to another medication.
  • Immunomodulators: These medications suppress the immune system response to prevent further inflammation. Immunomodulators can take several months to start working. People may use them if aminosalicylates and corticosteroids are not effective in causing remission of UC.
  • JAK inhibitors: These drugs suppress the immune system. They block an enzyme called the JAK enzyme, which causes inflammation. People may take JAK inhibitors to help treat moderate to severe UC.
  • Biologics: These medications are protein-based and come from naturally occurring materials. Biologics are antibodies that prevent certain proteins within the body from causing inflammation. They can help treat moderate to severe UC.

Diets

A person should discuss any dietary changes they are considering making with their doctor. Medical treatment may be more effective in preventing symptoms than dietary changes.

The Crohn’s and Colitis Foundation suggests the following diets may be helpful in managing IBD symptoms:

  • carbohydrate exclusion diet
  • Mediterranean diet
  • low fiber diet
  • low fermentable, oligo-, di-, monosaccharides, and polyols (FODMAP) diet

Ulcerative colitis is an immune-mediated or autoimmune inflammatory condition in which the immune system attacks healthy tissue in the gut. This causes inflammation of the large intestine, which causes the symptoms of UC.

Without proper treatment, UC could compromise the immune system. Certain medications to help treat UC may also suppress the immune system.

People can discuss with their doctor the benefits and risks of certain treatments for UC and any dietary changes that may help manage UC symptoms.